Prompt a message if an error occurs?

[bsaby]

The current behavior is that the extension will not be forced to jump to the checkstyle output channel when an error occurs.

Enhancements:
Currently, If the checkstyle output channel is not open, prompt a message:

1. Tell user that an error occurred
2. Provide a checkstyle output channel entry and ask the user if open it.

[jdneo]

This is a great suggestion. Let me think about how should the extension pop up the error hint.

[jdneo]

Current thinking about this:

The checkstyle status icon will have three status:

• X: has checkstyle error
• ✔️: no checkstyle error
• ⚠️: Something error occurred on checkstyle language server

[jdneo]

In #88, we change the status icon into 4 state:

• ✔️ No Checkstyle error, click it will open the output channel.
• 🐞 Has Checkstyle error, click it will open the output channel.
• ⚠️ Language server error, click it will open the output channel.
• ✏️ Wait for check, click it will trigger the command check code with Checkstyle.

@bsaby for awareness