Send Diagnostic information on InitializationError

[onlynone]

I noticed that if one of my files had an error that caused an error on initialization (say including a file that doesn't exist). Then the whole language server would crash. I also noticed that the IDE didn't show where the issue was located. I had to look into the "Output" tab and go through the large error logs and backtrace.

I made the changes included in this MR to the ruby-lsp-rails gem directly on my system, and it enabled me to see the problem right in the "Problems" tab, and it underlined the problem line directly in the editor.

I'm guessing this code isn't structured as the project might want, but I figured this would demonstrate the issue being encountered and provide a jumping off point where maybe the maintainers could make a better version.