Don't send info output to stderr

[clason]

LanguageServer.jl (and some of its dependent packages) send (all?!) info output (such as the timing summary or the packages loaded from cache) to stderr, which leads to quickly ballooning log files in clients such as Neovim since these messages are treated as actual errors.

As these are not error messages, they should be emitted accordingly (stdout, or ideally as actual LSP notifications).

[davidanthoff]

We can't send anything to stdout as that is used for the actual JSONRPC commutation.

Also, stderr seems exactly the right place to send (non error) log output to? In VS Code for example that ends up in the log output view for the LS which is super helpful. I guess you could run the Ls with a different log level if you don't want to see these messages?

[clason]

I guess you could run the Ls with a different log level if you don't want to see these messages?

That is exactly what I'm doing; I don't expect to see these messages with a log level set to "ERROR". (No other server sends "INFO" messages by default.)

(Obviously, you could say the server is still WIP, so any use would be testing and debugging, but...)

[clason]

(And the LSP has a dedicated notification for this: https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#window_logMessage and https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#logTrace)