if (!$fhandle->fdopen(*STDERR, "a"))

I'm not really sure if it can be used like that... the documentation says:

       $io->fdopen ( FD, MODE )
           "fdopen" is like an ordinary "open" except that its first p
+arameter is not a filename but rather a file han-
           dle name, an IO::Handle object, or a file descriptor number
+.
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I don't know if a typeglob is acceptable there. OTOH if it were not one would expect the call to fail... isn't it that *STDERR is being considered numeric and equal to 0 there?

$ perl -le 'print 0+*STDERR'
0
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Mind you, I'm just wild-guessing... in doubt try with fileno STDERR (==2 if you haven't changed it!)