Partial fix for missing file crash.

[jojorne]

This skips the missing file. So, the user still needs to F5. I see it as a fix when able to detect the file back without F5.

[jojorne]

The FileSystemWatcher is known to have several issues, I mean, more like unexpected behavior like double calls and unable to pay attention to missing folders and directories. I think if we want it to behaves the way we want, we need to wrap it somehow.