Feature request: error messages

currently most error messages when debugging scripts are pretty good with giving the line the error occurred on.
eg: expected variable name (line 10 column 30)

Except for the following:
“invalid item number”

I’d personally like to see the error be output in this case as “invalid item number (line 10 column 30)” like the other errors.
Also it would be great to have a function that lets you run through a script line by line to debug.

Regards,
Omega-00