Fix TypeError: Cannot read property 'length' of undefined

at _convertToBatch dynamics-web-api/lib/requests/sendRequest.js:117:40

The problem happens because we nullify _batchRequestId too early,
before the batch request is made. With _batchRequestId it generates a
new requestId, other than all operations were saved to, thus it crashes

Author: Kukunin

lib/dynamics-web-api.js

@@ -1474,11 +1474,12 @@ function DynamicsWebApi(config) {
 		request.collection = '$batch';
 
 		_isBatch = false;
-		_batchRequestId = null;
-		return _makeRequest('POST', request, 'executeBatch')
+		const promise = _makeRequest('POST', request, 'executeBatch')
 			.then(function (response) {
 				return response.data;
 			});
+		_batchRequestId = null;
+		return promise;
 	};
 
     /**