Given the the file handle is actually is, error is coming from the condition for while ...

#  cat p.pl ; perl p.pl

use strict;

open FH , '<' , $0 or die "open failed: $!";

while( FH )
{
  last;
}

close FH or die "close failed: $!";

__END__

Bareword "FH" not allowed while "strict subs" in use at p.pl line 11.
Execution of p.pl aborted due to compilation errors
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... despite the line number reported. open & close can deal with a bareword file handle but not loop condition.