Brief summary of issue / Description of requested feature:

Mudlet becomes unresponsive and crashes after using cut() function

Steps to reproduce the issue / Reasons for adding feature:

1. in command line put: lua selectString(line, 1) cut()
2. I had to run that line a few times actually when recreating this
3. Mudlet does not respond anymore and closes soon after

Error output / Expected result of feature

3. Mudlet should not crash, instead announce some error message

Extra information, such as Mudlet version, operating system and ideas for how to solve / implement:

Mudlet 4.10 and current PTB on Win