Skip adding the diff file ID if there's no content_sha

app/assets/javascripts/diffs/utils/diff_file.js

@@ -48,7 +48,10 @@ export function prepareRawDiffFile({ file, allFiles, meta = false }) {
     },
   };
 
-  if (!meta) {
+  // It's possible, but not confirmed, that `content_sha` isn't available sometimes
+  // See: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/49506#note_464692057
+  // We don't want duplicate IDs if that's the case, so we just don't assign an ID
+  if (!meta && file.content_sha) {
     additionalProperties.id = identifier(file);
   }
 

spec/frontend/diffs/utils/diff_file_spec.js

@@ -99,5 +99,18 @@ describe('diff_file utilities', () => {
 
       expect(preppedFile).not.toHaveProp('id');
     });
+
+    it('does not set the id property if the file is missing a `content_sha`', () => {
+      const fileMissingContentSha = { ...files[0] };
+
+      delete fileMissingContentSha.content_sha;
+
+      const preppedFile = prepareRawDiffFile({
+        file: fileMissingContentSha,
+        allFiles: files,
+      });
+
+      expect(preppedFile).not.toHaveProp('id');
+    });
   });
 });