Append stack trace to every language server error

[TwitchBronBron]

The language server sometimes throws error messages, but the language server output window in vscode does not show the stack trace, which makes these errors harder to track down.

Notable changes:

• adds a decorator for use in LanguageServer.ts that monitors for failures, and appends the stack trace to the error.message.

Here's what the new errors look like in the console: