Instead of debugging, code just stops running

I have a macro that gets to a point where it should hit an error and debug
but instead it just stops running. I can then access the spreadsheet and
make any changes I want, which I shouldn't be able to do. Any ideas why this
is happening? The error is coming because the macro tries to update links to
an external worksheet but the current spreadsheet is not linked to the
external one.

Thanks

Adam Bush