Mention --debug when a crash occurred

Author: jfmengels

lib/error-message.js

@@ -51,12 +51,14 @@ function report(options, err, defaultPath) {
 function unexpectedError(err) {
   const error = new CustomError(
     'UNEXPECTED ERROR',
+    // prettier-ignore
     `I ran into an unexpected error. Please open an issue at the following link:
   https://github.com/jfmengels/node-elm-review/issues/new
 
-Please include this error message and as much detail as you can provide. If you
-can, please provide a setup that makes it easy to reproduce the error. That will
-make it much easier to fix the issue.
+Please include this error message and as much detail as you can provide. Running
+with ${chalk.yellow('--debug')} might give additional information. If you can, please provide a
+setup that makes it easy to reproduce the error. That will make it much easier
+to fix the issue.
 
 Below is the error that was encountered.
 --------------------------------------------------------------------------------