Persisting *openBinaryFile* error on file delete

[ArturB]

After deleting opened source file, the extension produces an error "openBinaryFile: does not exist". Such an "orphaned" error is - as far as I know - impossible to dismiss otherwise than by restarting VS Code, as managing an error lifecycle in VS Code is the sole responsibility of extension that created it, and feature requests to add manual cleanup were repeatedly ignored by VS Code team.

Steps to reproduce:

1. Create new Stack project with stack new command.
2. Open ./src/Lib.hs file.
3. Delete ./src/Lib.hs.

My OS is Fedora 33.

[fendor]

Closing for inactivity, also likely not the fault of vscode-haskell. Feel free to reopen if this issue still persists.