LSP: Handle clients that do not support CompletionContext

(cherry picked from commit 0080d6f109d769478b049a0b3621183f8df71776)

modules/gdscript/language_server/godot_lsp.h

@@ -1440,7 +1440,7 @@ struct CompletionContext {
 	/**
 	 * How the completion was triggered.
 	 */
-	int triggerKind = CompletionTriggerKind::TriggerCharacter;
+	int triggerKind = CompletionTriggerKind::Invoked;
 
 	/**
 	 * The trigger character (a single character) that has trigger code complete.
@@ -1463,8 +1463,11 @@ struct CompletionParams : public TextDocumentPositionParams {
 
 	void load(const Dictionary &p_params) {
 		TextDocumentPositionParams::load(p_params);
+
+		if (p_params.has("context")) {
 			context.load(p_params["context"]);
 		}
+	}
 
 	Dictionary to_json() {
 		Dictionary ctx;