🧹fix: Handle Abort Message Edge Cases (#1462)

* chore: bump langchain to v0.0.213 from v0.0.186

* fix: handle abort edge cases:
- abort message server-side if response experienced error mid-generation
- attempt to recover message if aborting resulted in error
- if abortKey is not provided, use conversationId if it exists
- if headers were already sent, send an Event stream message
- issue warning for possible Google censor/filter

refactor(streamResponse): for `sendError`, allow passing overrides so that error can include partial generation, improve typing for `sendMessage`

* chore(MessageContent): remove eslint warning for unused `i`, rephrase unfinished message text

* fix(useSSE): avoid invoking cancelHandler if the abort response was 404

* chore(TMessage): remove unnecessary, unused legacy message property `submitting`

* chore(TMessage): remove unnecessary legacy message property `cancelled`

* chore(abortMiddleware): remove unused `errorText` property to avoid confusion

client/src/components/Chat/Messages/Content/MessageContent.tsx

@@ -35,7 +35,7 @@ const DisplayMessage = ({ text, isCreatedByUser, message, showCursor }: TDisplay
   return (
     <Container>
       {imageFiles &&
-        imageFiles.map((file, i) => (
+        imageFiles.map((file) => (
           <Image
             key={file.file_id}
             imagePath={file.preview ?? file.filepath ?? ''}
@@ -64,7 +64,7 @@ const DisplayMessage = ({ text, isCreatedByUser, message, showCursor }: TDisplay
 
 // Unfinished Message Component
 const UnfinishedMessage = () => (
-  <ErrorMessage text="This is an unfinished message. The AI may still be generating a response, it was aborted, or a censor was triggered. Refresh or visit later to see more updates." />
+  <ErrorMessage text="The response is incomplete; it's either still processing, was cancelled, or censored. Refresh or try a different prompt." />
 );
 
 // Content Component