Fix: Graceful error handling - never show blank responses on errors

app/backend/main.py

@@ -172,8 +172,18 @@ async def chat(request: ChatRequest):
     except HTTPException:
         raise
     except Exception as e:
-        logger.error(f"Error processing chat request: {str(e)}")
-        raise HTTPException(status_code=500, detail=f"Internal server error: {str(e)}")
+        logger.error(f"Error processing chat request: {str(e)}", exc_info=True)
+        # Return a proper ChatResponse with error info instead of a 500,
+        # so the frontend always has something to display.
+        return ChatResponse(
+            answer="I'm sorry, I encountered an unexpected error while processing your question. Please try again in a moment.",
+            sources=[],
+            route="error",
+            user_role=request.user_role,
+            accessible_collections=[],
+            guardrail_flags=["server_error"],
+            guardrail_warnings=[f"Internal error: {str(e)}"],
+        )
 
 
 # ====================

app/backend/pipeline/rag_pipeline.py

@@ -58,6 +58,27 @@ class RAGPipeline:
         Returns:
             RAGResponse with answer, sources, and metadata
         """
+        try:
+            return self._process_query(user_role, query_text, user_id)
+        except Exception as e:
+            logger.error(f"Unexpected error in RAG pipeline: {str(e)}", exc_info=True)
+            return RAGResponse(
+                answer="I'm sorry, I encountered an unexpected error while processing your question. Please try again in a moment.",
+                sources=[],
+                route="error",
+                user_role=user_role,
+                accessible_collections=[],
+                guardrail_flags=["pipeline_error"],
+                guardrail_warnings=[f"Internal error: {str(e)}"],
+            )
+    
+    def _process_query(
+        self,
+        user_role: str,
+        query_text: str,
+        user_id: Optional[str] = None,
+    ) -> RAGResponse:
+        """Internal query processing. Separated so answer_query can wrap with try/except."""
         metadata = QueryMetadata(
             user_role=user_role,
             user_department=self._get_department(user_role),
@@ -187,9 +208,9 @@ class RAGPipeline:
         # Generate answer
         answer = self._generate_answer(query_text, context, user_role)
         
-        if not answer:
+        if not answer or not answer.strip():
             return RAGResponse(
-                answer="I encountered an error while generating a response.",
+                answer="I wasn't able to generate a response for your question. Please try rephrasing or ask a different question.",
                 sources=[],
                 route=route_name,
                 user_role=user_role,

app/frontend-nextjs/components/ChatInterface.tsx

@@ -61,21 +61,35 @@ export default function ChatInterface({ user, onLogout, onAdminPanel }: ChatInte
         user_id: user.username,
       });
 
+      // Guard against empty/blank responses from the backend
+      const answerText = response.answer?.trim()
+        ? response.answer
+        : "I wasn't able to generate a response for your question. Please try rephrasing or ask a different question.";
+
       const assistantMessage: ChatMessageType = {
         id: (Date.now() + 1).toString(),
         type: 'assistant',
-        content: response.answer,
+        content: answerText,
         timestamp: new Date(),
-        response,
+        response: { ...response, answer: answerText },
       };
 
       setMessages((prev) => [...prev, assistantMessage]);
-    } catch (error) {
+    } catch (error: unknown) {
+      // Extract a helpful message from the error if possible
+      let errorText = 'Sorry, I encountered an error processing your query. Please try again in a moment.';
+      if (error && typeof error === 'object' && 'response' in error) {
+        const axiosError = error as { response?: { data?: { error?: string; detail?: string } } };
+        const serverMsg = axiosError.response?.data?.detail || axiosError.response?.data?.error;
+        if (serverMsg) {
+          errorText = `Sorry, something went wrong: ${serverMsg}`;
+        }
+      }
+
       const errorMessage: ChatMessageType = {
         id: (Date.now() + 1).toString(),
         type: 'assistant',
-        content:
-          'Sorry, I encountered an error processing your query. Please ensure the backend is running on http://localhost:8000',
+        content: errorText,
         timestamp: new Date(),
       };
       setMessages((prev) => [...prev, errorMessage]);