* fix: package.main with -- arguments
Fixes#1758
The combination of using a package.main (which sets the script
position to index zero) and using the -- stop slurp meant that
the arguments had the script appended to the end instead of
prepended to the start. The net result meant that when the script
was forked, it would drop the first user arg.
See diff for details of the fix - a simple check against null.
* fix: protect against missing opts
2967726673