diff --git a/ext/web/00_infra.js b/ext/web/00_infra.js
index 4b241ab5d7..9a75f8fa58 100644
--- a/ext/web/00_infra.js
+++ b/ext/web/00_infra.js
@@ -271,7 +271,7 @@ function addPaddingToBase64url(base64url) {
   if (base64url.length % 4 === 2) return base64url + "==";
   if (base64url.length % 4 === 3) return base64url + "=";
   if (base64url.length % 4 === 1) {
-    throw new TypeError("Illegal base64url string!");
+    throw new TypeError("Illegal base64url string");
   }
   return base64url;
 }
@@ -382,7 +382,7 @@ function assert(cond, msg = "Assertion failed.") {
 function serializeJSValueToJSONString(value) {
   const result = JSONStringify(value);
   if (result === undefined) {
-    throw new TypeError("Value is not JSON serializable.");
+    throw new TypeError("Value is not JSON serializable");
   }
   return result;
 }
@@ -429,7 +429,7 @@ function pathFromURLWin32(url) {
  */
 function pathFromURLPosix(url) {
   if (url.hostname !== "") {
-    throw new TypeError(`Host must be empty.`);
+    throw new TypeError("Host must be empty");
   }
 
   return decodeURIComponent(
@@ -444,7 +444,7 @@ function pathFromURLPosix(url) {
 function pathFromURL(pathOrUrl) {
   if (ObjectPrototypeIsPrototypeOf(URLPrototype, pathOrUrl)) {
     if (pathOrUrl.protocol != "file:") {
-      throw new TypeError("Must be a file URL.");
+      throw new TypeError("Must be a file URL");
     }
 
     return core.build.os == "windows"
diff --git a/ext/web/02_event.js b/ext/web/02_event.js
index a3e40ab996..f6351c4b9e 100644
--- a/ext/web/02_event.js
+++ b/ext/web/02_event.js
@@ -1031,11 +1031,11 @@ class EventTarget {
     }
 
     if (getDispatched(event)) {
-      throw new DOMException("Invalid event state.", "InvalidStateError");
+      throw new DOMException("Invalid event state", "InvalidStateError");
     }
 
     if (event.eventPhase !== Event.NONE) {
-      throw new DOMException("Invalid event state.", "InvalidStateError");
+      throw new DOMException("Invalid event state", "InvalidStateError");
     }
 
     return dispatch(self, event);
diff --git a/ext/web/03_abort_signal.js b/ext/web/03_abort_signal.js
index ae0701451b..93b3cf0522 100644
--- a/ext/web/03_abort_signal.js
+++ b/ext/web/03_abort_signal.js
@@ -196,7 +196,7 @@ class AbortSignal extends EventTarget {
 
   constructor(key = null) {
     if (key !== illegalConstructorKey) {
-      throw new TypeError("Illegal constructor.");
+      throw new TypeError("Illegal constructor");
     }
     super();
   }
diff --git a/ext/web/04_global_interfaces.js b/ext/web/04_global_interfaces.js
index 8483a7b238..7c7f83b431 100644
--- a/ext/web/04_global_interfaces.js
+++ b/ext/web/04_global_interfaces.js
@@ -16,7 +16,7 @@ const illegalConstructorKey = Symbol("illegalConstructorKey");
 class Window extends EventTarget {
   constructor(key = null) {
     if (key !== illegalConstructorKey) {
-      throw new TypeError("Illegal constructor.");
+      throw new TypeError("Illegal constructor");
     }
     super();
   }
@@ -29,7 +29,7 @@ class Window extends EventTarget {
 class WorkerGlobalScope extends EventTarget {
   constructor(key = null) {
     if (key != illegalConstructorKey) {
-      throw new TypeError("Illegal constructor.");
+      throw new TypeError("Illegal constructor");
     }
     super();
   }
@@ -42,7 +42,7 @@ class WorkerGlobalScope extends EventTarget {
 class DedicatedWorkerGlobalScope extends WorkerGlobalScope {
   constructor(key = null) {
     if (key != illegalConstructorKey) {
-      throw new TypeError("Illegal constructor.");
+      throw new TypeError("Illegal constructor");
     }
     super();
   }
diff --git a/ext/web/05_base64.js b/ext/web/05_base64.js
index b97846b904..e6796e1dc3 100644
--- a/ext/web/05_base64.js
+++ b/ext/web/05_base64.js
@@ -50,7 +50,7 @@ function btoa(data) {
   } catch (e) {
     if (ObjectPrototypeIsPrototypeOf(TypeErrorPrototype, e)) {
       throw new DOMException(
-        "The string to be encoded contains characters outside of the Latin1 range.",
+        "Cannot encode string: string contains characters outside of the Latin1 range",
         "InvalidCharacterError",
       );
     }
diff --git a/ext/web/06_streams.js b/ext/web/06_streams.js
index 57a437e4f5..e673ee2bb4 100644
--- a/ext/web/06_streams.js
+++ b/ext/web/06_streams.js
@@ -523,10 +523,14 @@ function dequeueValue(container) {
 function enqueueValueWithSize(container, value, size) {
   assert(container[_queue] && typeof container[_queueTotalSize] === "number");
   if (isNonNegativeNumber(size) === false) {
-    throw new RangeError("chunk size isn't a positive number");
+    throw new RangeError(
+      "Cannot enqueue value with size: chunk size must be a positive number",
+    );
   }
   if (size === Infinity) {
-    throw new RangeError("chunk size is invalid");
+    throw new RangeError(
+      "Cannot enqueue value with size: chunk size is invalid",
+    );
   }
   container[_queue].enqueue({ value, size });
   container[_queueTotalSize] += size;
@@ -1097,7 +1101,7 @@ async function readableStreamCollectIntoUint8Array(stream) {
 
     if (TypedArrayPrototypeGetSymbolToStringTag(chunk) !== "Uint8Array") {
       throw new TypeError(
-        "Can't convert value to Uint8Array while consuming the stream",
+        "Cannot convert value to Uint8Array while consuming the stream",
       );
     }
 
@@ -1347,7 +1351,7 @@ function readableByteStreamControllerEnqueue(controller, chunk) {
 
   if (isDetachedBuffer(buffer)) {
     throw new TypeError(
-      "chunk's buffer is detached and so cannot be enqueued",
+      "Chunk's buffer is detached and so cannot be enqueued",
     );
   }
   const transferredBuffer = ArrayBufferPrototypeTransferToFixedLength(buffer);
@@ -2095,14 +2099,14 @@ function readableByteStreamControllerRespond(controller, bytesWritten) {
   if (state === "closed") {
     if (bytesWritten !== 0) {
       throw new TypeError(
-        "bytesWritten must be 0 when calling respond() on a closed stream",
+        `"bytesWritten" must be 0 when calling respond() on a closed stream: received ${bytesWritten}`,
       );
     }
   } else {
     assert(state === "readable");
     if (bytesWritten === 0) {
       throw new TypeError(
-        "bytesWritten must be greater than 0 when calling respond() on a readable stream",
+        '"bytesWritten" must be greater than 0 when calling respond() on a readable stream',
       );
     }
     if (
@@ -2110,7 +2114,7 @@ function readableByteStreamControllerRespond(controller, bytesWritten) {
         // deno-lint-ignore prefer-primordials
         firstDescriptor.byteLength
     ) {
-      throw new RangeError("bytesWritten out of range");
+      throw new RangeError('"bytesWritten" out of range');
     }
   }
   firstDescriptor.buffer = ArrayBufferPrototypeTransferToFixedLength(
@@ -2305,7 +2309,7 @@ function readableByteStreamControllerRespondWithNewView(controller, view) {
   if (state === "closed") {
     if (byteLength !== 0) {
       throw new TypeError(
-        "The view's length must be 0 when calling respondWithNewView() on a closed stream",
+        `The view's length must be 0 when calling respondWithNewView() on a closed stream: received ${byteLength}`,
       );
     }
   } else {
@@ -3577,7 +3581,7 @@ function setUpReadableByteStreamControllerFromUnderlyingSource(
   }
   const autoAllocateChunkSize = underlyingSourceDict["autoAllocateChunkSize"];
   if (autoAllocateChunkSize === 0) {
-    throw new TypeError("autoAllocateChunkSize must be greater than 0");
+    throw new TypeError('"autoAllocateChunkSize" must be greater than 0');
   }
   setUpReadableByteStreamController(
     stream,
@@ -3706,7 +3710,7 @@ function setUpReadableStreamDefaultControllerFromUnderlyingSource(
  */
 function setUpReadableStreamBYOBReader(reader, stream) {
   if (isReadableStreamLocked(stream)) {
-    throw new TypeError("ReadableStream is locked.");
+    throw new TypeError("ReadableStream is locked");
   }
   if (
     !(ObjectPrototypeIsPrototypeOf(
@@ -3727,7 +3731,7 @@ function setUpReadableStreamBYOBReader(reader, stream) {
  */
 function setUpReadableStreamDefaultReader(reader, stream) {
   if (isReadableStreamLocked(stream)) {
-    throw new TypeError("ReadableStream is locked.");
+    throw new TypeError("ReadableStream is locked");
   }
   readableStreamReaderGenericInitialize(reader, stream);
   reader[_readRequests] = new Queue();
@@ -3961,7 +3965,7 @@ function setUpWritableStreamDefaultControllerFromUnderlyingSink(
  */
 function setUpWritableStreamDefaultWriter(writer, stream) {
   if (isWritableStreamLocked(stream) === true) {
-    throw new TypeError("The stream is already locked.");
+    throw new TypeError("The stream is already locked");
   }
   writer[_stream] = stream;
   stream[_writer] = writer;
@@ -4019,7 +4023,7 @@ function transformStreamDefaultControllerEnqueue(controller, chunk) {
       /** @type {ReadableStreamDefaultController<O>} */ readableController,
     ) === false
   ) {
-    throw new TypeError("Readable stream is unavailable.");
+    throw new TypeError("Readable stream is unavailable");
   }
   try {
     readableStreamDefaultControllerEnqueue(
@@ -5143,7 +5147,7 @@ class ReadableStream {
     if (underlyingSourceDict.type === "bytes") {
       if (strategy.size !== undefined) {
         throw new RangeError(
-          `${prefix}: When underlying source is "bytes", strategy.size must be undefined.`,
+          `${prefix}: When underlying source is "bytes", strategy.size must be 'undefined'`,
         );
       }
       const highWaterMark = extractHighWaterMark(strategy, 0);
@@ -5273,10 +5277,10 @@ class ReadableStream {
     const { readable, writable } = transform;
     const { preventClose, preventAbort, preventCancel, signal } = options;
     if (isReadableStreamLocked(this)) {
-      throw new TypeError("ReadableStream is already locked.");
+      throw new TypeError("ReadableStream is already locked");
     }
     if (isWritableStreamLocked(writable)) {
-      throw new TypeError("Target WritableStream is already locked.");
+      throw new TypeError("Target WritableStream is already locked");
     }
     const promise = readableStreamPipeTo(
       this,
@@ -5814,7 +5818,7 @@ class ReadableByteStreamController {
     }
     if (this[_stream][_state] !== "readable") {
       throw new TypeError(
-        "ReadableByteStreamController's stream is not in a readable state.",
+        "ReadableByteStreamController's stream is not in a readable state",
       );
     }
     readableByteStreamControllerClose(this);
@@ -5846,7 +5850,7 @@ class ReadableByteStreamController {
     if (byteLength === 0) {
       throw webidl.makeException(
         TypeError,
-        "length must be non-zero",
+        "Length must be non-zero",
         prefix,
         arg1,
       );
@@ -5854,19 +5858,19 @@ class ReadableByteStreamController {
     if (getArrayBufferByteLength(buffer) === 0) {
       throw webidl.makeException(
         TypeError,
-        "buffer length must be non-zero",
+        "Buffer length must be non-zero",
         prefix,
         arg1,
       );
     }
     if (this[_closeRequested] === true) {
       throw new TypeError(
-        "Cannot enqueue chunk after a close has been requested.",
+        "Cannot enqueue chunk after a close has been requested",
       );
     }
     if (this[_stream][_state] !== "readable") {
       throw new TypeError(
-        "Cannot enqueue chunk when underlying stream is not readable.",
+        "Cannot enqueue chunk when underlying stream is not readable",
       );
     }
     return readableByteStreamControllerEnqueue(this, chunk);
@@ -6006,7 +6010,7 @@ class ReadableStreamDefaultController {
   close() {
     webidl.assertBranded(this, ReadableStreamDefaultControllerPrototype);
     if (readableStreamDefaultControllerCanCloseOrEnqueue(this) === false) {
-      throw new TypeError("The stream controller cannot close or enqueue.");
+      throw new TypeError("The stream controller cannot close or enqueue");
     }
     readableStreamDefaultControllerClose(this);
   }
@@ -6021,7 +6025,7 @@ class ReadableStreamDefaultController {
       chunk = webidl.converters.any(chunk);
     }
     if (readableStreamDefaultControllerCanCloseOrEnqueue(this) === false) {
-      throw new TypeError("The stream controller cannot close or enqueue.");
+      throw new TypeError("The stream controller cannot close or enqueue");
     }
     readableStreamDefaultControllerEnqueue(this, chunk);
   }
@@ -6146,12 +6150,12 @@ class TransformStream {
     );
     if (transformerDict.readableType !== undefined) {
       throw new RangeError(
-        `${prefix}: readableType transformers not supported.`,
+        `${prefix}: readableType transformers not supported`,
       );
     }
     if (transformerDict.writableType !== undefined) {
       throw new RangeError(
-        `${prefix}: writableType transformers not supported.`,
+        `${prefix}: writableType transformers not supported`,
       );
     }
     const readableHighWaterMark = extractHighWaterMark(readableStrategy, 0);
@@ -6356,7 +6360,7 @@ class WritableStream {
     );
     if (underlyingSinkDict.type != null) {
       throw new RangeError(
-        `${prefix}: WritableStream does not support 'type' in the underlying sink.`,
+        `${prefix}: WritableStream does not support 'type' in the underlying sink`,
       );
     }
     initializeWritableStream(this);
@@ -6483,7 +6487,7 @@ class WritableStreamDefaultWriter {
     webidl.assertBranded(this, WritableStreamDefaultWriterPrototype);
     if (this[_stream] === undefined) {
       throw new TypeError(
-        "A writable stream is not associated with the writer.",
+        "A writable stream is not associated with the writer",
       );
     }
     return writableStreamDefaultWriterGetDesiredSize(this);
diff --git a/ext/web/10_filereader.js b/ext/web/10_filereader.js
index 05b45202d6..2718606380 100644
--- a/ext/web/10_filereader.js
+++ b/ext/web/10_filereader.js
@@ -65,7 +65,7 @@ class FileReader extends EventTarget {
     // 1. If fr's state is "loading", throw an InvalidStateError DOMException.
     if (this[state] === "loading") {
       throw new DOMException(
-        "Invalid FileReader state.",
+        "Invalid FileReader state",
         "InvalidStateError",
       );
     }
diff --git a/ext/web/12_location.js b/ext/web/12_location.js
index 2cda9f719c..ba0c47e2d1 100644
--- a/ext/web/12_location.js
+++ b/ext/web/12_location.js
@@ -28,7 +28,7 @@ const locationConstructorKey = Symbol("locationConstructorKey");
 class Location {
   constructor(href = null, key = null) {
     if (key != locationConstructorKey) {
-      throw new TypeError("Illegal constructor.");
+      throw new TypeError("Illegal constructor");
     }
     const url = new URL(href);
     url.username = "";
@@ -41,7 +41,7 @@ class Location {
         },
         set() {
           throw new DOMException(
-            `Cannot set "location.hash".`,
+            `Cannot set "location.hash"`,
             "NotSupportedError",
           );
         },
@@ -54,7 +54,7 @@ class Location {
         },
         set() {
           throw new DOMException(
-            `Cannot set "location.host".`,
+            `Cannot set "location.host"`,
             "NotSupportedError",
           );
         },
@@ -67,7 +67,7 @@ class Location {
         },
         set() {
           throw new DOMException(
-            `Cannot set "location.hostname".`,
+            `Cannot set "location.hostname"`,
             "NotSupportedError",
           );
         },
@@ -80,7 +80,7 @@ class Location {
         },
         set() {
           throw new DOMException(
-            `Cannot set "location.href".`,
+            `Cannot set "location.href"`,
             "NotSupportedError",
           );
         },
@@ -100,7 +100,7 @@ class Location {
         },
         set() {
           throw new DOMException(
-            `Cannot set "location.pathname".`,
+            `Cannot set "location.pathname"`,
             "NotSupportedError",
           );
         },
@@ -113,7 +113,7 @@ class Location {
         },
         set() {
           throw new DOMException(
-            `Cannot set "location.port".`,
+            `Cannot set "location.port"`,
             "NotSupportedError",
           );
         },
@@ -126,7 +126,7 @@ class Location {
         },
         set() {
           throw new DOMException(
-            `Cannot set "location.protocol".`,
+            `Cannot set "location.protocol"`,
             "NotSupportedError",
           );
         },
@@ -139,7 +139,7 @@ class Location {
         },
         set() {
           throw new DOMException(
-            `Cannot set "location.search".`,
+            `Cannot set "location.search"`,
             "NotSupportedError",
           );
         },
@@ -161,7 +161,7 @@ class Location {
         __proto__: null,
         value: function assign() {
           throw new DOMException(
-            `Cannot call "location.assign()".`,
+            `Cannot call "location.assign()"`,
             "NotSupportedError",
           );
         },
@@ -171,7 +171,7 @@ class Location {
         __proto__: null,
         value: function reload() {
           throw new DOMException(
-            `Cannot call "location.reload()".`,
+            `Cannot call "location.reload()"`,
             "NotSupportedError",
           );
         },
@@ -181,7 +181,7 @@ class Location {
         __proto__: null,
         value: function replace() {
           throw new DOMException(
-            `Cannot call "location.replace()".`,
+            `Cannot call "location.replace()"`,
             "NotSupportedError",
           );
         },
@@ -229,7 +229,7 @@ const workerLocationUrls = new SafeWeakMap();
 class WorkerLocation {
   constructor(href = null, key = null) {
     if (key != locationConstructorKey) {
-      throw new TypeError("Illegal constructor.");
+      throw new TypeError("Illegal constructor");
     }
     const url = new URL(href);
     url.username = "";
@@ -244,7 +244,7 @@ ObjectDefineProperties(WorkerLocation.prototype, {
     get() {
       const url = WeakMapPrototypeGet(workerLocationUrls, this);
       if (url == null) {
-        throw new TypeError("Illegal invocation.");
+        throw new TypeError("Illegal invocation");
       }
       return url.hash;
     },
@@ -256,7 +256,7 @@ ObjectDefineProperties(WorkerLocation.prototype, {
     get() {
       const url = WeakMapPrototypeGet(workerLocationUrls, this);
       if (url == null) {
-        throw new TypeError("Illegal invocation.");
+        throw new TypeError("Illegal invocation");
       }
       return url.host;
     },
@@ -268,7 +268,7 @@ ObjectDefineProperties(WorkerLocation.prototype, {
     get() {
       const url = WeakMapPrototypeGet(workerLocationUrls, this);
       if (url == null) {
-        throw new TypeError("Illegal invocation.");
+        throw new TypeError("Illegal invocation");
       }
       return url.hostname;
     },
@@ -280,7 +280,7 @@ ObjectDefineProperties(WorkerLocation.prototype, {
     get() {
       const url = WeakMapPrototypeGet(workerLocationUrls, this);
       if (url == null) {
-        throw new TypeError("Illegal invocation.");
+        throw new TypeError("Illegal invocation");
       }
       return url.href;
     },
@@ -292,7 +292,7 @@ ObjectDefineProperties(WorkerLocation.prototype, {
     get() {
       const url = WeakMapPrototypeGet(workerLocationUrls, this);
       if (url == null) {
-        throw new TypeError("Illegal invocation.");
+        throw new TypeError("Illegal invocation");
       }
       return url.origin;
     },
@@ -304,7 +304,7 @@ ObjectDefineProperties(WorkerLocation.prototype, {
     get() {
       const url = WeakMapPrototypeGet(workerLocationUrls, this);
       if (url == null) {
-        throw new TypeError("Illegal invocation.");
+        throw new TypeError("Illegal invocation");
       }
       return url.pathname;
     },
@@ -316,7 +316,7 @@ ObjectDefineProperties(WorkerLocation.prototype, {
     get() {
       const url = WeakMapPrototypeGet(workerLocationUrls, this);
       if (url == null) {
-        throw new TypeError("Illegal invocation.");
+        throw new TypeError("Illegal invocation");
       }
       return url.port;
     },
@@ -328,7 +328,7 @@ ObjectDefineProperties(WorkerLocation.prototype, {
     get() {
       const url = WeakMapPrototypeGet(workerLocationUrls, this);
       if (url == null) {
-        throw new TypeError("Illegal invocation.");
+        throw new TypeError("Illegal invocation");
       }
       return url.protocol;
     },
@@ -340,7 +340,7 @@ ObjectDefineProperties(WorkerLocation.prototype, {
     get() {
       const url = WeakMapPrototypeGet(workerLocationUrls, this);
       if (url == null) {
-        throw new TypeError("Illegal invocation.");
+        throw new TypeError("Illegal invocation");
       }
       return url.search;
     },
@@ -352,7 +352,7 @@ ObjectDefineProperties(WorkerLocation.prototype, {
     value: function toString() {
       const url = WeakMapPrototypeGet(workerLocationUrls, this);
       if (url == null) {
-        throw new TypeError("Illegal invocation.");
+        throw new TypeError("Illegal invocation");
       }
       return url.href;
     },
@@ -414,7 +414,7 @@ const locationDescriptor = {
     return location;
   },
   set() {
-    throw new DOMException(`Cannot set "location".`, "NotSupportedError");
+    throw new DOMException(`Cannot set "location"`, "NotSupportedError");
   },
   enumerable: true,
 };
@@ -422,7 +422,7 @@ const workerLocationDescriptor = {
   get() {
     if (workerLocation == null) {
       throw new Error(
-        `Assertion: "globalThis.location" must be defined in a worker.`,
+        `Assertion: "globalThis.location" must be defined in a worker`,
       );
     }
     return workerLocation;
diff --git a/ext/web/15_performance.js b/ext/web/15_performance.js
index 9e0e310a57..f23e851246 100644
--- a/ext/web/15_performance.js
+++ b/ext/web/15_performance.js
@@ -123,14 +123,14 @@ function convertMarkToTimestamp(mark) {
     const entry = findMostRecent(mark, "mark");
     if (!entry) {
       throw new DOMException(
-        `Cannot find mark: "${mark}".`,
+        `Cannot find mark: "${mark}"`,
         "SyntaxError",
       );
     }
     return entry.startTime;
   }
   if (mark < 0) {
-    throw new TypeError("Mark cannot be negative.");
+    throw new TypeError(`Mark cannot be negative: received ${mark}`);
   }
   return mark;
 }
@@ -261,7 +261,9 @@ class PerformanceMark extends PerformanceEntry {
     super(name, "mark", startTime, 0, illegalConstructorKey);
     this[webidl.brand] = webidl.brand;
     if (startTime < 0) {
-      throw new TypeError("startTime cannot be negative");
+      throw new TypeError(
+        `Cannot construct PerformanceMark: startTime cannot be negative, received ${startTime}`,
+      );
     }
     this[_detail] = structuredClone(detail);
   }
@@ -504,14 +506,14 @@ class Performance extends EventTarget {
       ObjectKeys(startOrMeasureOptions).length > 0
     ) {
       if (endMark) {
-        throw new TypeError("Options cannot be passed with endMark.");
+        throw new TypeError('Options cannot be passed with "endMark"');
       }
       if (
         !ReflectHas(startOrMeasureOptions, "start") &&
         !ReflectHas(startOrMeasureOptions, "end")
       ) {
         throw new TypeError(
-          "A start or end mark must be supplied in options.",
+          'A "start" or "end" mark must be supplied in options',
         );
       }
       if (
@@ -520,7 +522,7 @@ class Performance extends EventTarget {
         ReflectHas(startOrMeasureOptions, "end")
       ) {
         throw new TypeError(
-          "Cannot specify start, end, and duration together in options.",
+          'Cannot specify "start", "end", and "duration" together in options',
         );
       }
     }
diff --git a/ext/web/16_image_data.js b/ext/web/16_image_data.js
index 2048f002d5..13df0d07be 100644
--- a/ext/web/16_image_data.js
+++ b/ext/web/16_image_data.js
@@ -84,35 +84,35 @@ class ImageData {
 
       if (dataLength === 0) {
         throw new DOMException(
-          "Failed to construct 'ImageData': The input data has zero elements.",
+          "Failed to construct 'ImageData': the input data has zero elements",
           "InvalidStateError",
         );
       }
 
       if (dataLength % 4 !== 0) {
         throw new DOMException(
-          "Failed to construct 'ImageData': The input data length is not a multiple of 4.",
+          `Failed to construct 'ImageData': the input data length is not a multiple of 4, received ${dataLength}`,
           "InvalidStateError",
         );
       }
 
       if (sourceWidth < 1) {
         throw new DOMException(
-          "Failed to construct 'ImageData': The source width is zero or not a number.",
+          "Failed to construct 'ImageData': the source width is zero or not a number",
           "IndexSizeError",
         );
       }
 
       if (webidl.type(sourceHeight) !== "Undefined" && sourceHeight < 1) {
         throw new DOMException(
-          "Failed to construct 'ImageData': The source height is zero or not a number.",
+          "Failed to construct 'ImageData': the source height is zero or not a number",
           "IndexSizeError",
         );
       }
 
       if (dataLength / 4 % sourceWidth !== 0) {
         throw new DOMException(
-          "Failed to construct 'ImageData': The input data length is not a multiple of (4 * width).",
+          "Failed to construct 'ImageData': the input data length is not a multiple of (4 * width)",
           "IndexSizeError",
         );
       }
@@ -122,7 +122,7 @@ class ImageData {
         (sourceWidth * sourceHeight * 4 !== dataLength)
       ) {
         throw new DOMException(
-          "Failed to construct 'ImageData': The input data length is not equal to (4 * width * height).",
+          "Failed to construct 'ImageData': the input data length is not equal to (4 * width * height)",
           "IndexSizeError",
         );
       }
@@ -159,14 +159,14 @@ class ImageData {
 
     if (sourceWidth < 1) {
       throw new DOMException(
-        "Failed to construct 'ImageData': The source width is zero or not a number.",
+        "Failed to construct 'ImageData': the source width is zero or not a number",
         "IndexSizeError",
       );
     }
 
     if (sourceHeight < 1) {
       throw new DOMException(
-        "Failed to construct 'ImageData': The source height is zero or not a number.",
+        "Failed to construct 'ImageData': the source height is zero or not a number",
         "IndexSizeError",
       );
     }
diff --git a/tests/specs/run/_070_location/070_location.ts.out b/tests/specs/run/_070_location/070_location.ts.out
index a03cf6477c..c5750973fb 100644
--- a/tests/specs/run/_070_location/070_location.ts.out
+++ b/tests/specs/run/_070_location/070_location.ts.out
@@ -11,5 +11,5 @@ Location {
   protocol: "https:",
   search: "?baz"
 }
-NotSupportedError: Cannot set "location".
-NotSupportedError: Cannot set "location.hostname".
+NotSupportedError: Cannot set "location"
+NotSupportedError: Cannot set "location.hostname"