One of the worst things about mutt is its debugging facilities. Binary search for errors in one's config is dumb. Not having config debugging compiled in by default is also dumb.
This leaves me with a mutt config that when I source it, mutt tells me there are errors. However, the misconfig is not apparent in my daily use. So, I'll just keep using it until I notice something not working and then I'll know where to look in my config.
That's fine for me. What about other people? Do I ask the arch linux guys to compile debug in? That'll probably detract from the small+fast mindset that is arch linux. Time to ask...
I compiled mutt 1.5.21 with debug support, and it appears to be a bug in 1.5.20 'source' command. Is it the case that all errors are reported? For random breakings of things in my config this appears true. So, I won't ask the arch maintainer to compile in debug support, even though it only adds 50KB to the binary size.