🧹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

api/app/clients/BaseClient.js

@@ -516,7 +516,7 @@ class BaseClient {
   }
 
   async saveMessageToDatabase(message, endpointOptions, user = null) {
-    await saveMessage({ ...message, user, unfinished: false, cancelled: false });
+    await saveMessage({ ...message, user, unfinished: false });
     await saveConvo(user, {
       conversationId: message.conversationId,
       endpoint: this.options.endpoint,