mod_compat_roles: Fix attempt to index a nil value #1847
permissions[] is not a map with role names as keys since 817bc9873fc2
but instead a level with host names were added. This was likely an
oversight.
Refactored towards railroad.
This module writes out a traceback to `traceback.txt` in Prosodys data
directory (see `prosodyctl about`) when the signal `SIGUSR1` is
received. This is useful when debugging seemingly frozen instances in
case it is stuck in Lua code.