What is this marked number Next to the File name in Visual Studio Code

Question

I know the meaning of M as "modified" on the right side of the file name.

But what is that number 4 next to the M ?

Is there a name for these marks?
Any docs of this will helpful!

Answer 1

That is the number of linting errors and warnings currently in the file.

To see the actual errors and their details, open the Problems panel, which by default is at the bottom part of the editor. (If it's not shown, open it by going to the menu View > Problems).

Answer 2

As @Goofballtech mentioned, this is the number of errors & warnings associated with a given file. You can turn this off by setting problems.decorations.enabled to false in your VSCode settings.json.

You can find more information here: https://code.visualstudio.com/updates/v1_20#_error-indicators-in-the-explorer