https://rt.cpan.org/Public/Bug/Display.html?id=58333
http://github.com/dap/Net-XMPP/commit/2d1164d7c50d7c034f3d1efb03ad9319b24dfd24

--- Net-XMPP-1.02/lib/Net/XMPP/Debug.pm
+++ Net-XMPP-1.02/lib/Net/XMPP/Debug.pm
@@ -151,7 +151,7 @@
     my %args;
     while($#_ >= 0) { $args{ lc pop(@_) } = pop(@_); }
 
-    delete($args{file}) if (lc($args{file}) eq "stdout");
+    delete($args{file}) if (defined $args{file} && lc($args{file}) eq "stdout");
 
     $args{time} = 0 if !exists($args{time});
     $args{setdefault} = 0 if !exists($args{setdefault});