Generated JS code: Closure compiler errors

[danfabi]

service.grpc.js:17: ERROR - extra require: 'proto.(message)' is never referenced in this file
goog.require('proto.(message)');

  ProTip: "JSC_EXTRA_REQUIRE_WARNING" or "extraRequire" or "legacyGoogScopeRequire" can be added to the `suppress` attribute of:
 //target
  Alternatively /** @suppress {legacyGoogScopeRequire} */ can be added to the source file.

[danfabi]

ERROR - could not determine the type of this expression
        error ? reject(error) : resolve(response);
        ^
  ProTip: "JSC_UNKNOWN_EXPR_TYPE" or "missingSourcesWarnings" or "reportUnknownTypes" can be added to the `suppress` attribute of:
//<target>

  Alternatively /** @suppress {reportUnknownTypes} */ can be added to the source file.

[danfabi]

Here is the generated source code:

/**
 * @param {!proto.(RequestMessage)} request The
 *     request proto
 * @param {!Object<string, string>} metadata User defined
 *     call metadata
 * @return {!Promise<!proto.(ResponseMessage)>}
 *     The XHR Node Readable Stream
 */
(package).prototype.index =
    function(request, metadata) {
  return new Promise((resolve, reject) => {
    this.delegateClient_.index(
      request, metadata, (error, response) => {
        error ? reject(error) : resolve(response);
      });
  });
};

[danfabi]

The same error repeats over and over for error, reject(error) and resolve(response).