Added validation to prevent sending empty messages

[jumang4423]

Overview

This pull request introduces a crucial feature to the chat feature. The update ensures that the application does not send empty messages, enhancing the overall user experience and maintaining the quality of the conversation.

Key Changes

• Validation Check: Implemented a validation check in the onSend function to prevent the sending of empty messages. This ensures that every message sent through the application has meaningful content.

Details

• The validation check is a simple conditional statement that returns from the onSend function if the userInput is empty. This small but significant change improves the quality of the conversations by preventing unnecessary empty messages.