[BUG]: shift -1 is not a valid option

[r1bilski]

Describe the bug

Running ytfzf with no arguments will attempt to call shift with negative argument. According to Open Group Base Specifications on shift, the argument must be an unsigned integer.
My shell yash, does not process -1 in POSIX mode.

To Reproduce

Run ytfzf with no arguments

Expected behavior

shift is not called with negative argumetn

Screenshots

Information

• OS: Artix Linux
• Terminal: alacritty 0.13.1
• Ytfzf version: master / 2.6.2
• Output of readlink $(which sh): yash (v2.55)
• (if is a thumbnail issue) run ytfzf --thumbnail-log=log.txt and post the file:

Additional context

https://pubs.opengroup.org/onlinepubs/009695399/

[Euro20179]

as mentioned there won't not be a new update so you should be safe just editing the file to fix it.