Catch substitution errors
[22:44:29] <Jerry> s/[/foo/
[22:44:42] <Jerry> ^ throws errors in #dnet.lua
[22:44:29] <U2> ./luascripts/subbot.lua:32: malformed pattern (missing ']')
[22:44:29] <U2> stack traceback:
[22:44:29] <U2> [C]: in function 'find'
[22:44:29] <U2> ./luascripts/subbot.lua:32: in function 'applySubstitution'
[22:44:29] <U2> ./luascripts/subbot.lua:89: in function 'onPublicMessage'
[22:44:29] <U2> ./luascripts/lib/base.lua:306: in function 'handlePublicMessage'
[22:44:29] <U2> ./luascripts/lib/base.lua:232: in function 'handle'
[22:44:29] <U2> ./luascripts/lib/base.lua:190: in function <./luascripts/lib/base.lua:190>