ChatInput: add a handler for when user send a message

J=CLIP-573
TEST=auto,manual

verified that if provided, onSend is executed after the user sends a message

src/components/ChatInput.tsx

@@ -94,8 +94,9 @@ export function ChatInput({
       ? chat.streamNextMessage(input)
       : chat.getNextMessage(input);
     setInput("");
-    if (onSend) res.then(() => {onSend(input)});
-    res.catch((e) => (handleError ? handleError(e) : defaultHandleApiError(e)));
+    res.then(() => {
+      onSend?.(input)
+    }).catch((e) => (handleError ? handleError(e) : defaultHandleApiError(e)));
   }, [chat, input, handleError, defaultHandleApiError, stream, onSend]);
 
   const handleKeyDown = useCallback(

tests/components/ChatInput.test.tsx

@@ -207,10 +207,10 @@ it("executes custom handleError if provided", async () => {
 });
 
 it("executes onSend if provided", async () => {
-  console.log = jest.fn();
-  render(<ChatInput onSend={message => console.log("Message: ", message)} />);
+  const onSendCb = jest.fn();
+  render(<ChatInput onSend={message => onSendCb(message)} />);
   await act(() => userEvent.type(screen.getByRole("textbox"), "test"));
   const sendButton = screen.getByRole("button");
   await act(() => userEvent.click(sendButton));
-  expect(console.log).toBeCalledWith("Message: ", "test");
+  expect(onSendCb).toBeCalledWith("test");
 });