Re^2: Perl 5.10.1 - compare external program output with a list of known error codes

I am getting this at the end of the perl output

Can't use an undefined value as a subroutine reference at ./error_chec
+ker.pl line 34.
[download]

The line 34 is this. I actually did not understand this as well

$errors{$program_output3}; # lowercase, just in case

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Re^3: Perl 5.10.1 - compare external program output with a list of known error codes by stevieb (Canon) on Sep 19, 2016 at 19:17 UTC
You missed the `->()` piece, which turns it into a function call: `$errors{$program_output3}->();` [download] it means, dereference `$errors{$program_output3}` as a `CREF` (code reference), and execute it.	[reply] [d/l] [select]