Update code to use environment variables and improve error handling

app.py

@@ -42,8 +42,11 @@ Try these examples:
 What would you like to know?"""
         
         # Send welcome message
-        msg = cl.Message(content=welcome_message)
-        await msg.send()
+        await cl.Message(
+            content=welcome_message,
+            author="Assistant",
+            type="text"
+        ).send()
         
         logger.info("Chat session started successfully")
     except Exception as e:
@@ -82,37 +85,48 @@ async def handle_message(message: cl.Message):
             # Add response to history
             history.append({"role": "assistant", "content": formatted_response})
             
-            # Create a message with proper formatting
-            elements = []
-            
             # Check if the response contains ticker suggestions
             if "Did you mean one of these?" in formatted_response:
                 # Split the response into main message and suggestions
                 main_msg, suggestions = formatted_response.split("Did you mean one of these?")
                 
                 # Send the main message
-                msg = cl.Message(content=main_msg.strip())
-                await msg.send()
+                await cl.Message(
+                    content=main_msg.strip(),
+                    author="Assistant",
+                    type="text"
+                ).send()
                 
                 # Create a list of suggestions
                 suggestion_list = suggestions.strip().split('\n')
+                elements = []
                 for suggestion in suggestion_list:
                     if suggestion.strip():
                         elements.append(cl.Text(name="Suggestion", content=suggestion.strip()))
                 
                 # Send the suggestions
                 if elements:
-                    msg = cl.Message(content="", elements=elements)
-                    await msg.send()
+                    await cl.Message(
+                        content="",
+                        elements=elements,
+                        author="Assistant",
+                        type="text"
+                    ).send()
             else:
                 # Send regular response
-                msg = cl.Message(content=formatted_response)
-                await msg.send()
+                await cl.Message(
+                    content=formatted_response,
+                    author="Assistant",
+                    type="text"
+                ).send()
         else:
             error_msg = "Received an invalid response format from the agent."
             logger.error(f"{error_msg} Response: {response}")
-            msg = cl.Message(content=error_msg)
-            await msg.send()
+            await cl.Message(
+                content=error_msg,
+                author="Assistant",
+                type="text"
+            ).send()
             
         # Update history in storage
         chat_histories[session_id] = history
@@ -120,8 +134,11 @@ async def handle_message(message: cl.Message):
     except Exception as e:
         error_msg = f"Error occurred: {str(e)}"
         logger.error(error_msg)
-        msg = cl.Message(content="Sorry, something went wrong while processing your request. Please try again.")
-        await msg.send()
+        await cl.Message(
+            content="Sorry, something went wrong while processing your request. Please try again.",
+            author="Assistant",
+            type="text"
+        ).send()
 
 @cl.on_chat_end
 async def end_chat():