LSP response encoding of DocumentSelect is wrong: is DocumentFilter, should be DocumentFilter[]

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Description

Hi,

I'm currently integrating ruby-lsp as an extension for the Nova editor and it raises an error early on because a response message couldn't be parsed.

Details and log can be found in the Nova Dev Forum here and also attached as a file here lsp-error.txt

This is what the offending response sent from ruby-lsp looks like

"documentSelector" : {
		"scheme" : "file",
		"language" : "ruby"
},

which leads to this error in Nova:

"Expected to decode Array<Any> but found a dictionary instead."

Looking at the error and JSON-RPC it appears to me that Nova is right and your encoding of DocumentSelector is not conforming to the LSP spec , where it is defined as :

DocumentSelector export type = DocumentFilter[];

I'm not very well versed in ruby so I can't provide a properly built and tested pull request, but I think I've tracked it down to the following line in your source code:

/lib/ruby_lsp/requests/semantic_highlighting.rb#L32 is

document_selector: { scheme: "file", language: "ruby" },

I can make it work fine if I patch it locally in my installed ruby-lsp gem to

document_selector: [ { scheme: "file", language: "ruby" } ],

obviously I couldn't test for any regressions, but I hope you can include a fix soon in an upcoming release

thanks, O