Error for invalid -l | -o options on the early stage instead of getting a cryptic error

[EmilyGraceSeville7cf]

This is my first PR here. :)

[agnostic-apollo]

Thanks for the validation checks.

I have fixed the following issues:

• Errors should be sent to stderr.
• Exit code via show_usage should not be 0 for errors.
• The help output would show the invalid value of $PARAM_LIMIT or $PARAM_OFFSET that was overridden instead of the default value.
• Variables should be quoted to prevent whitespace splitting.

Kindly test the changes as I have not. Will squash and merge once that is done.

[EmilyGraceSeville7cf]

It seems to work as expected. 😄