in reply to trap run time errors

The usual form of that message is something like: Use of uninitialized value in say at line 1, <STDIN> line 4.

Which says (in this case) that the uninitialised value occurred in a say statement at line 1 of the source file whilst processing line 4 of input from standard in.

The full error message should tell you what lines of your source and data files caused the error. What more information do you need?

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In Section Seekers of Perl Wisdom