Previous errors aren't cleared when the config file becomes invalid

[roblourens]

Testing microsoft/vscode#12602

• Have a js file with some eslint error decorations visible.
• Edit the eslintrc.json to be invalid
• A warning is printed to the Output, but the error decorations are still visible, even if the code is edited to address them.
• If I reopen the editor, then the errors are gone.

It seems like all decorations should be cleared when the extension is no longer checking. Is that possible?

[dbaeumer]

Need to think about this. The problem is that if the user types in that file you don't want to clear them.