Erased messages should not stall attachment jobs

ts/messageModifiers/AttachmentDownloads.ts

@@ -286,12 +286,15 @@ async function _runJob(job?: AttachmentDownloadJobType): Promise<void> {
         Errors.toLogFormat(error)
       );
 
+      try {
         await _addAttachmentToMessage(
           message,
           _markAttachmentAsTransientError(attachment),
           { type, index }
         );
+      } finally {
         await _finishJob(message, id);
+      }
 
       return;
     }
@@ -302,6 +305,7 @@ async function _runJob(job?: AttachmentDownloadJobType): Promise<void> {
       Errors.toLogFormat(error)
     );
 
+    try {
       // Remove `pending` flag from the attachment.
       await _addAttachmentToMessage(
         message,
@@ -326,9 +330,11 @@ async function _runJob(job?: AttachmentDownloadJobType): Promise<void> {
       };
 
       await saveAttachmentDownloadJob(failedJob);
+    } finally {
       delete _activeAttachmentDownloadJobs[id];
       _maybeStartJob();
     }
+  }
 }
 
 async function _finishJob(