The callback may be undefined

Author: axelrindle

index.d.ts

@@ -93,5 +93,5 @@ type CallbackFunction = (error?: Error, update?: ReleaseDescriptor | TagDescript
 
 type RestHandlerFunction = (res: IncomingMessage) => void
 
-export default function check(options: CheckOptions, callback: CallbackFunction): null | Promise<ReleaseDescriptor | TagDescriptor>
+export default function check(options: CheckOptions, callback?: CallbackFunction): null | Promise<ReleaseDescriptor | TagDescriptor>
 export = check

lib/main.js

@@ -5,8 +5,8 @@ const check = require('./check')
  * The exported checking function.
  *
  * @param {CheckOptions} options The options for the version check.
- * @param {CallbackFunction} callback An optional callback to pass the result to.
- *                                      Can be omitted to return a Promise.
+ * @param {CallbackFunction|undefined} callback An optional callback to pass the result to.
+ *                                              Can be omitted to return a Promise.
  * @return null or a Promise.
  */
 module.exports = (options, callback) => {