🧹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/models/Message.js

@@ -18,7 +18,6 @@ module.exports = {
     isCreatedByUser = false,
     error,
     unfinished,
-    cancelled,
     files,
     isEdited = false,
     finish_reason = null,
@@ -45,7 +44,6 @@ module.exports = {
         finish_reason,
         error,
         unfinished,
-        cancelled,
         tokenCount,
         plugin,
         plugins,

api/models/schema/messageSchema.js

@@ -68,10 +68,6 @@ const messageSchema = mongoose.Schema(
       type: Boolean,
       default: false,
     },
-    cancelled: {
-      type: Boolean,
-      default: false,
-    },
     error: {
       type: Boolean,
       default: false,