lib/srdb1 Prevent crash in case of incorrect parameter

Reported by clang.

lib/srdb1/db_id.c

@@ -207,12 +207,14 @@ static int parse_db_url(struct db_id* id, const str* url)
 	return 0;
 
  err:
+	if (!id) goto end;
 	if (id->scheme) pkg_free(id->scheme);
 	if (id->username) pkg_free(id->username);
 	if (id->password) pkg_free(id->password);
 	if (id->host) pkg_free(id->host);
 	if (id->database) pkg_free(id->database);
 	if (prev_token) pkg_free(prev_token);
+ end:
 	return -1;
 }