Provide some diagnostics of internal error
Provide some diagnostics of internal error

Summary: Now print at least rule name.

Reviewed By: mzlee

shipit-source-id: d28f4acfa1c0110d9990c9bc0a3e1dfefc820038

JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck,JoelMarcey/buck