Leaving the organization question to other respondents, you (and at least one respondent) made a common mistake. GetOptions() can report 1 or more errors via warn() and then return a false value. Because there can be more than 1 error, it doesn't use die(). So it is your responsibility to stop execution for such cases.

GetOptions(
    # ...
) or exit 1;
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Or use a die() as shown in Getopt::Long.