do not warn on false-but-blessed exceptions

While some consider this not best practice, blessed objects that overload to a
false result are legitimate and should not be prevented.

Author: karenetheridge

lib/Test2/Tools/Exception.pm

@@ -21,7 +21,7 @@ sub dies(&) {
 
     return undef if $ok;
 
-    unless ($err) {
+    unless (not ref($err) and $err) {
         my $ctx = context();
         $ctx->alert("Got exception as expected, but exception is falsy (undef, '', or 0)...");
         $ctx->release;