GDScript: Fix crash when superclass file is non-existent

Incidentally, allow EOF to be an end of statement.

modules/gdscript/gdscript_cache.cpp

@@ -85,6 +85,17 @@ Error GDScriptParserRef::raise_status(Status p_new_status) {
 				return result;
 			}
 		}
+		if (result != OK) {
+			if (parser != nullptr) {
+				memdelete(parser);
+				parser = nullptr;
+			}
+			if (analyzer != nullptr) {
+				memdelete(analyzer);
+				analyzer = nullptr;
+			}
+			return result;
+		}
 	}
 
 	return result;
@@ -118,6 +129,10 @@ Ref<GDScriptParserRef> GDScriptCache::get_parser(const String &p_path, GDScriptP
 	if (singleton->parser_map.has(p_path)) {
 		ref = singleton->parser_map[p_path];
 	} else {
+		if (!FileAccess::exists(p_path)) {
+			r_error = ERR_FILE_NOT_FOUND;
+			return ref;
+		}
 		GDScriptParser *parser = memnew(GDScriptParser);
 		ref.instance();
 		ref->parser = parser;

modules/gdscript/gdscript_parser.cpp

@@ -466,17 +466,17 @@ void GDScriptParser::pop_multiline() {
 }
 
 bool GDScriptParser::is_statement_end() {
-	return check(GDScriptTokenizer::Token::NEWLINE) || check(GDScriptTokenizer::Token::SEMICOLON);
+	return check(GDScriptTokenizer::Token::NEWLINE) || check(GDScriptTokenizer::Token::SEMICOLON) || check(GDScriptTokenizer::Token::TK_EOF);
 }
 
 void GDScriptParser::end_statement(const String &p_context) {
 	bool found = false;
-	while (is_statement_end()) {
+	while (is_statement_end() && !is_at_end()) {
 		// Remove sequential newlines/semicolons.
 		found = true;
 		advance();
 	}
-	if (!found) {
+	if (!found && !is_at_end()) {
 		push_error(vformat(R"(Expected end of statement after %s, found "%s" instead.)", p_context, current.get_name()));
 	}
 }