Do not panic and improve error message on cache failure (#3784)

cli/disk_cache.rs

@@ -13,6 +13,13 @@ pub struct DiskCache {
   pub location: PathBuf,
 }
 
+fn with_io_context<T: AsRef<str>>(
+  e: &std::io::Error,
+  context: T,
+) -> std::io::Error {
+  std::io::Error::new(e.kind(), format!("{} (for '{}')", e, context.as_ref()))
+}
+
 impl DiskCache {
   pub fn new(location: &Path) -> Self {
     // TODO: ensure that 'location' is a directory
@@ -107,10 +114,12 @@ impl DiskCache {
   pub fn set(&self, filename: &Path, data: &[u8]) -> std::io::Result<()> {
     let path = self.location.join(filename);
     match path.parent() {
-      Some(ref parent) => fs::create_dir_all(parent),
+      Some(ref parent) => fs::create_dir_all(parent)
+        .map_err(|e| with_io_context(&e, format!("{:#?}", &path))),
       None => Ok(()),
     }?;
     deno_fs::write_file(&path, data, 0o666)
+      .map_err(|e| with_io_context(&e, format!("{:#?}", &path)))
   }
 
   pub fn remove(&self, filename: &Path) -> std::io::Result<()> {

cli/file_fetcher.rs

@@ -28,6 +28,28 @@ use std::sync::Mutex;
 use url;
 use url::Url;
 
+pub fn source_header_cache_failed_error(
+  module_name: &str,
+  reason: &str,
+) -> ErrBox {
+  DenoError::new(
+    ErrorKind::Other,
+    format!(
+      "Source code header cache failed for '{}': {}",
+      module_name, reason
+    ),
+  )
+  .into()
+}
+
+pub fn source_cache_failed_error(module_name: &str, reason: &str) -> ErrBox {
+  DenoError::new(
+    ErrorKind::Other,
+    format!("Source code cache failed for '{}': {}", module_name, reason),
+  )
+  .into()
+}
+
 /// Structure representing local or remote file.
 ///
 /// In case of remote file `url` might be different than originally requested URL, if so
@@ -416,14 +438,17 @@ impl SourceFileFetcher {
         }
         FetchOnceResult::Redirect(new_module_url) => {
           // If redirects, update module_name and filename for next looped call.
-          dir
-            .save_source_code_headers(
+          if let Err(e) = dir.save_source_code_headers(
             &module_url,
             None,
             Some(new_module_url.to_string()),
             None,
-            )
-            .unwrap();
+          ) {
+            return Err(source_header_cache_failed_error(
+              module_url.as_str(),
+              &e.to_string(),
+            ));
+          }
 
           // Explicit drop to keep reference alive until future completes.
           drop(download_job);
@@ -440,16 +465,24 @@ impl SourceFileFetcher {
         }
         FetchOnceResult::Code(source, maybe_content_type, etag) => {
           // We land on the code.
-          dir
-            .save_source_code_headers(
+          if let Err(e) = dir.save_source_code_headers(
             &module_url,
             maybe_content_type.clone(),
             None,
             etag,
-            )
-            .unwrap();
+          ) {
+            return Err(source_header_cache_failed_error(
+              module_url.as_str(),
+              &e.to_string(),
+            ));
+          }
 
-          dir.save_source_code(&module_url, &source).unwrap();
+          if let Err(e) = dir.save_source_code(&module_url, &source) {
+            return Err(source_cache_failed_error(
+              module_url.as_str(),
+              &e.to_string(),
+            ));
+          }
 
           let filepath = dir
             .deps_cache