Add missing error handlers on stream pipelines

- AnonymizedFile.anonymizedContent(): propagate content errors to the
  anonymizer so callers see the failure instead of hanging.
- AnonymizedFile.send() local path: add error handler on the anonymizer
  transform between content and response pipes.
- S3.send(): handle errors on the S3 body stream to avoid unhandled
  emits crashing the process.
- S3.archive() / FileSystem.archive(): propagate read-stream errors
  to the file transformer so archiver sees the failure.
- Add frontend translations for new error codes.

public/i18n/locale-en.json

@@ -103,7 +103,9 @@
     "username_not_defined": "A username must be provided.",
     "github_user_not_found": "The specified GitHub user could not be found.",
     "cannot_coauthor_self": "You cannot add yourself as a co-author.",
-    "storage_write_size_mismatch": "The downloaded file was smaller than expected. The upstream source may have returned an incomplete response — please try again."
+    "storage_write_size_mismatch": "The downloaded file was smaller than expected. The upstream source may have returned an incomplete response — please try again.",
+    "storage_read_error": "An error occurred while reading the file from storage — please try again.",
+    "upstream_error": "A temporary error occurred while fetching from GitHub — please try again."
   },
   "WARNINGS": {
     "page_not_enabled_on_repo": "GitHub Pages is not enabled on this repository. Enable it in the repository's Settings → Pages on GitHub, then refresh.",

src/core/AnonymizedFile.ts

@@ -269,6 +269,7 @@ export default class AnonymizedFile {
     if (!config.STREAMER_ENTRYPOINT) {
       // collect the content locally
       const content = await this.content();
+      content.on("error", (err) => anonymizer.destroy(err));
       return content.pipe(anonymizer);
     }
 
@@ -412,6 +413,7 @@ export default class AnonymizedFile {
         content
           .on("error", handleStreamError)
           .pipe(anonymizer)
+          .on("error", handleStreamError)
           .pipe(res)
           .on("error", handleStreamError)
           .on("finish", () => {

src/core/storage/FileSystem.ts

@@ -228,10 +228,12 @@ export default class FileSystem extends StorageBase {
 
     await this.listFiles(repoId, dir, {
       onEntry: async (file) => {
-        let rs = await this.read(repoId, file.path);
+        let rs: Readable = await this.read(repoId, file.path);
         if (opt?.fileTransformer) {
-          // apply transformation on the stream
+          const src = rs;
-          rs = rs.pipe(opt.fileTransformer(file.path));
+          const transformer = opt.fileTransformer(file.path);
+          src.on("error", (err) => transformer.destroy(err));
+          rs = src.pipe(transformer);
         }
         const f = file.path.replace(fullPath, "");
         archive.append(rs, {

src/core/storage/S3.ts

@@ -124,7 +124,13 @@ export default class S3Storage extends StorageBase {
         res.set("Content-Length", s.ContentLength.toString());
       }
       if (s.Body) {
-        (s.Body as Readable)?.pipe(res);
+        const body = s.Body as Readable;
+        body.on("error", (err) => {
+          logger.error("S3 body stream error", { ...serializeError(err), filePath: path });
+          if (!res.headersSent) res.status(502).json({ error: "storage_read_error" });
+          else res.destroy();
+        });
+        body.pipe(res);
       } else {
         res.end();
       }
@@ -344,10 +350,12 @@ export default class S3Storage extends StorageBase {
           f.Key.replace(join(this.repoPath(repoId), dir), "")
         );
 
-        let rs = await this.read(repoId, f.Key);
+        let rs: Readable = await this.read(repoId, f.Key);
         if (opt?.fileTransformer) {
-          // apply transformation on the stream
+          const src = rs;
-          rs = rs.pipe(opt.fileTransformer(f.Key));
+          const transformer = opt.fileTransformer(f.Key);
+          src.on("error", (err) => transformer.destroy(err));
+          rs = src.pipe(transformer);
         }
 
         archive.append(rs, {