[commands] CommandError derived exceptions in checks don't crash help.
[commands] CommandError derived exceptions in checks don't crash help.

lgkern/PriestPy,rapptz/discord.py,Harmon758/discord.py,Harmon758/discord.py,khazhyk/discord.py,imayhaveborkedit/discord.py,Rapptz/discord.py,jhgg/discord.py,variablehair/Eggplantato,Theoretical/UselessBot,mgardne8/discord.py