diff --git a/core/01_core.js b/core/01_core.js
index 21376b695b..0e823f54a8 100644
--- a/core/01_core.js
+++ b/core/01_core.js
@@ -17,6 +17,7 @@
     Promise,
     ObjectFromEntries,
     MapPrototypeGet,
+    MapPrototypeHas,
     MapPrototypeDelete,
     MapPrototypeSet,
     PromisePrototypeThen,
diff --git a/core/02_error.js b/core/02_error.js
index 85c287102f..d061164e7e 100644
--- a/core/02_error.js
+++ b/core/02_error.js
@@ -15,156 +15,81 @@
     ArrayPrototypeJoin,
   } = window.__bootstrap.primordials;
 
-  // Some of the code here is adapted directly from V8 and licensed under a BSD
-  // style license available here: https://github.com/v8/v8/blob/24886f2d1c565287d33d71e4109a53bf0b54b75c/LICENSE.v8
-  function patchCallSite(callSite, location) {
-    return {
-      getThis() {
-        return callSite.getThis();
-      },
-      getTypeName() {
-        return callSite.getTypeName();
-      },
-      getFunction() {
-        return callSite.getFunction();
-      },
-      getFunctionName() {
-        return callSite.getFunctionName();
-      },
-      getMethodName() {
-        return callSite.getMethodName();
-      },
-      getFileName() {
-        return location.fileName;
-      },
-      getLineNumber() {
-        return location.lineNumber;
-      },
-      getColumnNumber() {
-        return location.columnNumber;
-      },
-      getEvalOrigin() {
-        return callSite.getEvalOrigin();
-      },
-      isToplevel() {
-        return callSite.isToplevel();
-      },
-      isEval() {
-        return callSite.isEval();
-      },
-      isNative() {
-        return callSite.isNative();
-      },
-      isConstructor() {
-        return callSite.isConstructor();
-      },
-      isAsync() {
-        return callSite.isAsync();
-      },
-      isPromiseAll() {
-        return callSite.isPromiseAll();
-      },
-      getPromiseIndex() {
-        return callSite.getPromiseIndex();
-      },
-    };
-  }
-
   // Keep in sync with `cli/fmt_errors.rs`.
-  function formatLocation(callSite) {
-    if (callSite.isNative()) {
+  function formatLocation(cse) {
+    if (cse.isNative) {
       return "native";
     }
-
     let result = "";
-
-    const fileName = callSite.getFileName();
-
-    if (fileName) {
-      result += core.opSync("op_format_file_name", fileName);
+    if (cse.fileName) {
+      result += core.opSync("op_format_file_name", cse.fileName);
     } else {
-      if (callSite.isEval()) {
-        const evalOrigin = callSite.getEvalOrigin();
-        if (evalOrigin == null) {
+      if (cse.isEval) {
+        if (cse.evalOrigin == null) {
           throw new Error("assert evalOrigin");
         }
-        result += `${evalOrigin}, `;
+        result += `${cse.evalOrigin}, `;
       }
       result += "<anonymous>";
     }
-
-    const lineNumber = callSite.getLineNumber();
-    if (lineNumber != null) {
-      result += `:${lineNumber}`;
-
-      const columnNumber = callSite.getColumnNumber();
-      if (columnNumber != null) {
-        result += `:${columnNumber}`;
+    if (cse.lineNumber != null) {
+      result += `:${cse.lineNumber}`;
+      if (cse.columnNumber != null) {
+        result += `:${cse.columnNumber}`;
       }
     }
-
     return result;
   }
 
   // Keep in sync with `cli/fmt_errors.rs`.
-  function formatCallSite(callSite) {
+  function formatCallSiteEval(cse) {
     let result = "";
-    const functionName = callSite.getFunctionName();
-
-    const isTopLevel = callSite.isToplevel();
-    const isAsync = callSite.isAsync();
-    const isPromiseAll = callSite.isPromiseAll();
-    const isConstructor = callSite.isConstructor();
-    const isMethodCall = !(isTopLevel || isConstructor);
-
-    if (isAsync) {
+    if (cse.isAsync) {
       result += "async ";
     }
-    if (isPromiseAll) {
-      result += `Promise.all (index ${callSite.getPromiseIndex()})`;
+    if (cse.isPromiseAll) {
+      result += `Promise.all (index ${cse.promiseIndex})`;
       return result;
     }
+    const isMethodCall = !(cse.isToplevel || cse.isConstructor);
     if (isMethodCall) {
-      const typeName = callSite.getTypeName();
-      const methodName = callSite.getMethodName();
-
-      if (functionName) {
-        if (typeName) {
-          if (!StringPrototypeStartsWith(functionName, typeName)) {
-            result += `${typeName}.`;
+      if (cse.functionName) {
+        if (cse.typeName) {
+          if (!StringPrototypeStartsWith(cse.functionName, cse.typeName)) {
+            result += `${cse.typeName}.`;
           }
         }
-        result += functionName;
-        if (methodName) {
-          if (!StringPrototypeEndsWith(functionName, methodName)) {
-            result += ` [as ${methodName}]`;
+        result += cse.functionName;
+        if (cse.methodName) {
+          if (!StringPrototypeEndsWith(cse.functionName, cse.methodName)) {
+            result += ` [as ${cse.methodName}]`;
           }
         }
       } else {
-        if (typeName) {
-          result += `${typeName}.`;
+        if (cse.typeName) {
+          result += `${cse.typeName}.`;
         }
-        if (methodName) {
-          result += methodName;
+        if (cse.methodName) {
+          result += cse.methodName;
         } else {
           result += "<anonymous>";
         }
       }
-    } else if (isConstructor) {
+    } else if (cse.isConstructor) {
       result += "new ";
-      if (functionName) {
-        result += functionName;
+      if (cse.functionName) {
+        result += cse.functionName;
       } else {
         result += "<anonymous>";
       }
-    } else if (functionName) {
-      result += functionName;
+    } else if (cse.functionName) {
+      result += cse.functionName;
     } else {
-      result += formatLocation(callSite);
+      result += formatLocation(cse);
       return result;
     }
 
-    result += ` (${formatLocation(callSite)})`;
+    result += ` (${formatLocation(cse)})`;
     return result;
   }
 
@@ -189,37 +114,24 @@
     };
   }
 
+  function sourceMapCallSiteEval(cse) {
+    if (cse.fileName && cse.lineNumber != null && cse.columnNumber != null) {
+      return { ...cse, ...core.opSync("op_apply_source_map", cse) };
+    }
+    return cse;
+  }
+
   /** A function that can be used as `Error.prepareStackTrace`. */
-  function prepareStackTrace(
-    error,
-    callSites,
-  ) {
-    const mappedCallSites = ArrayPrototypeMap(callSites, (callSite) => {
-      const fileName = callSite.getFileName();
-      const lineNumber = callSite.getLineNumber();
-      const columnNumber = callSite.getColumnNumber();
-      if (fileName && lineNumber != null && columnNumber != null) {
-        return patchCallSite(
-          callSite,
-          core.opSync("op_apply_source_map", {
-            fileName,
-            lineNumber,
-            columnNumber,
-          }),
-        );
-      }
-      return callSite;
-    });
+  function prepareStackTrace(error, callSites) {
+    let callSiteEvals = ArrayPrototypeMap(callSites, evaluateCallSite);
+    callSiteEvals = ArrayPrototypeMap(callSiteEvals, sourceMapCallSiteEval);
     ObjectDefineProperties(error, {
       __callSiteEvals: { value: [], configurable: true },
     });
     const formattedCallSites = [];
-    for (const callSite of mappedCallSites) {
-      ArrayPrototypePush(error.__callSiteEvals, evaluateCallSite(callSite));
-      ArrayPrototypePush(
-        formattedCallSites,
-        formatCallSite(callSite),
-      );
+    for (const cse of callSiteEvals) {
+      ArrayPrototypePush(error.__callSiteEvals, cse);
+      ArrayPrototypePush(formattedCallSites, formatCallSiteEval(cse));
     }
     const message = error.message !== undefined ? error.message : "";
     const name = error.name !== undefined ? error.name : "Error";