How to use the promise-polyfill.reject function in promise-polyfill

Dropbox.prototype.addTemplate = function (path) {

    if (!path) {
        return Promise.reject(null);
    }

    const ext = extname(path);
    if (!(ext in Template.Parsers)) {
        return Promise.reject(
            new Error(`Incorrect extension ${ext} for template`)
        );
    }

    return this.download(path).then((data) => {
         const tmpl = Template.Parsers[ext](data);
         const name = basename(path, true).split('_').pop();

         // Avoid duplicates
         let uniqueName = name, i = 1;
         while (uniqueName in this._templates) {
             uniqueName = `${name}-${i}`;
             i++;
         }

         this._templates[uniqueName] = tmpl;

return Promise.reject(exc);
    }
  } catch (error) {
    log.warn(error);
  }
  // Use extra transport - img
  // Send only part when using gif
  const smallMsg = (msg.service === SERVICE_TRACK)
    ? this.options.msgCropper(msg) : msg;
  log(`sending using IMG. useSafe: ${useSafe}`, smallMsg);

  try {
    return this.sendIMG(this.makeURL(imgPath, objectAssign(smallMsg, this.creds)));
  } catch (e) {
    log('Error during sending data using image', e);
    return Promise.reject(e);
  }
};

// user sendBeacon only for notifications requests
    else if (this.options.allowSendBeacon && hasBeaconSupport && !isRequest) {
      log('sending using beacon');
      nav.sendBeacon(this.makeURL(postPath), data);
      return Promise.resolve();
    }
    // regular XMLHttpRequest
    else if (this.options.allowXHR && hasAnyXRSupport) {
      log('sending using XHR/XDR');
      return this.sendXHR(this.makeURL(postPath), data);
    }
    // If reuquired response but not available transport
    else if (isRequest) {
      const exc = new Error('Not available transport for request');
      log.error(exc)
      return Promise.reject(exc);
    }
  } catch (error) {
    log.warn(error);
  }
  // Use extra transport - img
  // Send only part when using gif
  const smallMsg = (msg.service === SERVICE_TRACK)
    ? this.options.msgCropper(msg) : msg;
  log(`sending using IMG. useSafe: ${useSafe}`, smallMsg);

  try {
    return this.sendIMG(this.makeURL(imgPath, objectAssign(smallMsg, this.creds)));
  } catch (e) {
    log('Error during sending data using image', e);
    return Promise.reject(e);
  }

.then(canvas => {
                                try {
                                    canvas
                                        .getContext('2d')
                                        .getImageData(0, 0, canvas.width, canvas.height);
                                } catch (e) {
                                    return Promise.reject('Canvas is tainted');
                                }

                                const delta = 10;

                                if (REFTEST && query.refTest === 'true') {
                                    const RESULTS = parseRefTest(result);
                                    REFTEST.forEach(({action, line, ...args}, i) => {
                                        const RESULT = RESULTS[i];
                                        expect(RESULT.action).to.equal(action, `Line ${line}`);

                                        const desc = `Line ${line} ${action}`;

                                        switch (action) {
                                            case 'Window':
                                                expect(RESULT.width).to.equal(
                                                    args.width,

handleError(error) {
        console.error('An error occurred', error);
        return Promise.reject(error.message || error);
    }

Fitter.prototype.update = function (type, id, lms) {
    if (!lms) {
        return Promise.reject(null);
    } else {
        return this.fit(type, id, lms, true);
    }

};

    : () => Promise.reject(errorOrFunction)

function fetchGlobalVendorList() {
	const {globalVendorListLocation} = config;

	return (globalVendorListLocation ?
		fetch(globalVendorListLocation) :
		Promise.reject('Missing globalVendorListLocation'))
		.then(res => res.json())
		.catch(() => {
			log.error(`Failed to load global vendor list from: ${globalVendorListLocation}`);
		});
}

Dropbox.prototype.fetchThumbnail = function () {
    return Promise.reject(null);
};

function fetchVendorList() {
	const {globalVendorListLocation} = config;
	return (globalVendorListLocation ?
		fetch(globalVendorListLocation) :
		Promise.reject('Missing globalVendorListLocation'))
		.then(res => res.json())
		.catch(() => {
			return sendPortalCommand({command: 'readVendorList'});
		});
}