The only place in the whole of AMX Mod X that that output can be generated is in the
set_fail_state() function. The "Plugin says" portion is the string provided to the set_fail_state() function.
Are you absolutely sure you're using that source code in your .amxx file? Did you compile it locally with official compilers?
If it's truly not this plugin then there would have to be a bug in the plugin pointer lookup (line) but I find that highly unlikely. Granted, if you're having a segmentation fault, I'm sure it's possible that it's just screwing up a whole bunch of stuff and presenting as a false error.