Prevent add-ons from exiting the server process (#3617)

Author: vinistock

lib/ruby_lsp/server.rb

@@ -115,7 +115,7 @@ def process_message(message)
       end
     rescue DelegateRequestError
       send_message(Error.new(id: message[:id], code: DelegateRequestError::CODE, message: "DELEGATE_REQUEST"))
-    rescue StandardError, LoadError => e
+    rescue StandardError, LoadError, SystemExit => e
       # If an error occurred in a request, we have to return an error response or else the editor will hang
       if message[:id]
         # If a document is deleted before we are able to process all of its enqueued requests, we will try to read it

test/server_test.rb

@@ -1605,6 +1605,48 @@ def test_something
     })
   end
 
+  def test_addons_are_unable_to_exit_the_server_process
+    Class.new(RubyLsp::Addon) do
+      def activate(global_state, outgoing_queue); end
+
+      def workspace_did_change_watched_files(changes)
+        exit
+      end
+
+      def name
+        "Bad add-on"
+      end
+
+      def deactivate; end
+
+      def version
+        "0.1.0"
+      end
+    end
+
+    @server.load_addons
+
+    begin
+      @server.global_state.index.index_all(uris: [])
+      @server.process_message({
+        method: "workspace/didChangeWatchedFiles",
+        params: {
+          changes: [
+            {
+              uri: URI::Generic.from_path(path: File.join(Dir.pwd, "lib", "server.rb")).to_s,
+              type: RubyLsp::Constant::FileChangeType::CHANGED,
+            },
+          ],
+        },
+      })
+      pass
+    rescue SystemExit
+      flunk("Add-on was able to exit the server process")
+    ensure
+      RubyLsp::Addon.unload_addons
+    end
+  end
+
   private
 
   def wait_for_indexing