Clean up draft messages in sendMessage error paths

Author: johnstcn

chat/src/components/chat-provider.tsx

@@ -280,6 +280,7 @@ export function ChatProvider({ children }: PropsWithChildren) {
       });
 
       if (!response.ok) {
+        setMessages((prev) => prev.filter((m) => !isDraftMessage(m)));
         const errorData = await response.json() as APIErrorModel;
         console.error("Failed to send message:", errorData);
         const detail = errorData.detail;
@@ -296,6 +297,7 @@ export function ChatProvider({ children }: PropsWithChildren) {
       }
 
     } catch (error) {
+      setMessages((prev) => prev.filter((m) => !isDraftMessage(m)));
       console.error("Error sending message:", error);
       const message = getErrorMessage(error)