testGetProtectedFunction() {
    const fn = () => {
      throw new Error('Foo');
    };
    /** @suppress {visibility} suppression added to enable type checking */
    const protectedFn = errorHandler.getProtectedFunction(fn);
    const e = assertThrows(protectedFn);
    assertTrue(e instanceof ErrorHandler.ProtectedFunctionError);
    assertEquals('Foo', e.cause.message);
  }
@suppress {strictMissingProperties} suppression added to enable type
     checking