🛡️ fix: Improve Error Handling and Null Safety in SSE Event Processing (#10751)

* 🔧 fix: Handle null content parts in message processing

- Added checks to filter out null content parts in various message handling functions, ensuring robustness against undefined values.
- Updated the `extractMessageContent`, `useContentHandler`, `useEventHandlers`, and `useStepHandler` hooks to prevent errors caused by null parts.
- Enhanced the `getAllContentText` utility to only include valid content types, improving overall message integrity.

* 🔧 fix: Enhance error handling in event and SSE handlers

- Wrapped critical sections in try-catch blocks within `useEventHandlers` and `useSSE` hooks to improve error management and prevent application crashes.
- Added console error logging for better debugging and tracking of issues during message processing and conversation aborting.
- Ensured that UI states like `setIsSubmitting` and `setShowStopButton` are correctly updated in case of errors, maintaining a consistent user experience.

* 🔧 fix: Filter out null and empty content in message export

- Enhanced the `useExportConversation` hook to filter out null content parts and empty strings during message processing, ensuring only valid content is included in the export.
- This change improves the integrity of exported conversations by preventing unnecessary empty entries in the output.

client/src/hooks/SSE/useSSE.ts

@@ -124,7 +124,13 @@ export default function useSSE(
       if (data.final != null) {
         clearDraft(submission.conversation?.conversationId);
         const { plugins } = data;
-        finalHandler(data, { ...submission, plugins } as EventSubmission);
+        try {
+          finalHandler(data, { ...submission, plugins } as EventSubmission);
+        } catch (error) {
+          console.error('Error in finalHandler:', error);
+          setIsSubmitting(false);
+          setShowStopButton(false);
+        }
         (startupConfig?.balance?.enabled ?? false) && balanceQuery.refetch();
         console.log('final', data);
         return;
@@ -187,14 +193,20 @@ export default function useSSE(
       setCompleted((prev) => new Set(prev.add(streamKey)));
       const latestMessages = getMessages();
       const conversationId = latestMessages?.[latestMessages.length - 1]?.conversationId;
-      return await abortConversation(
-        conversationId ??
-          userMessage.conversationId ??
-          submission.conversation?.conversationId ??
-          '',
-        submission as EventSubmission,
-        latestMessages,
-      );
+      try {
+        await abortConversation(
+          conversationId ??
+            userMessage.conversationId ??
+            submission.conversation?.conversationId ??
+            '',
+          submission as EventSubmission,
+          latestMessages,
+        );
+      } catch (error) {
+        console.error('Error during abort:', error);
+        setIsSubmitting(false);
+        setShowStopButton(false);
+      }
     });
 
     sse.addEventListener('error', async (e: MessageEvent) => {