message: Fix Catastrophic backtracking of arg regex
diff: @@ -230,7 +230,7 @@ export class Completer implements vscode.CompletionItemProvider {
  provider = this.command
  break
  case 'argument':
  - reg = args.document.languageId === 'latex-expl3' ? /\\([a-zA-Z_@]*(?::[a-zA-Z]*)?)((?:\[(?:\[.*?\]|{.*?}|.)*?\]|{(?:\[.*?\]|{.*?}|.)*?})*)[[{][^[\]{}]*$/ : /\\(\+?[a-zA-Z]*)((?:\[(?:\[.*?\]|{.*?}|.)*?\]|{(?:\[.*?\]|{.*?}|.)*?})*)[[{][^[\]{}]*$/
  + reg = args.document.languageId === 'latex-expl3' ? /\\([a-zA-Z_@]*(?::[a-zA-Z]*)?)((?:\[.*?\]|{.*?})*)[[{][^[\]{}]*$/ : /\\(\+?[a-zA-Z]*)((?:\[.*?\]|{.*?})*)[[{][^[\]{}]*$/
  provider = this.argument
  break
  case 'package':
  