Don't log errors for NonExistingDocumentError

These are expected to happen.
VSCode extensions can registers additional uri schemes
for which they provide content for.
These do not exist on disk which means the server will not find  them in the index.

Happens since Shopify#2334

Also adds a test that virtual documents raise the same error
https://code.visualstudio.com/api/extension-guides/virtual-documents
https://code.visualstudio.com/api/references/document-selector#document-scheme

Closes Shopify#2384

lib/ruby_lsp/server.rb

@@ -118,10 +118,9 @@ def process_message(message)
               backtrace: e.backtrace&.join("\n"),
             },
           ))
+          $stderr.puts("Error processing #{message[:method]}: #{e.full_message}")
         end
       end
-
-      $stderr.puts("Error processing #{message[:method]}: #{e.full_message}")
     end
 
     sig { void }

lib/ruby_lsp/store.rb

@@ -38,8 +38,9 @@ def get(uri)
       document = @state[uri.to_s]
       return document unless document.nil?
 
-      # For unsaved files (`untitled:Untitled-1` uris), there's no path to read from. If we don't have the untitled file
-      # already present in the store, then we have to raise non existing document error
+      # For unsaved files (`untitled:Untitled-1` uris) or virtual documents (extension-contributed schemes), there's no
+      # path to read from. If we don't have the untitled file already present in the store, then we have to raise
+      # non existing document error
       path = uri.to_standardized_path
       raise NonExistingDocumentError, uri.to_s unless path
 

test/store_test.rb

@@ -238,4 +238,12 @@ def test_raises_non_existing_document_error_on_unknown_unsaved_files
       @store.get(URI("untitled:Untitled-1"))
     end
   end
+
+  def test_raises_non_existing_document_error_for_virtual_documents
+    uri =
+      "sorbet:https%3A//github.com/sorbet/sorbet/tree/090ed6096a83dd7a5fe52bd3f9338c1eca5178eb/rbi/core/constants.rbi"
+    assert_raises(RubyLsp::Store::NonExistingDocumentError) do
+      @store.get(URI(uri))
+    end
+  end
 end