Disallow sending of empty messages
Disallow sending of empty messages

We previously checked for the message string not to be '' but we also
need to account for whitespace.

sirodoht/ting,odyvarv/ting-1,VitSalis/ting,odyvarv/ting-1,dionyziz/ting,sirodoht/ting,mbalamat/ting,gtklocker/ting,sirodoht/ting,gtklocker/ting,gtklocker/ting,mbalamat/ting,VitSalis/ting,dionyziz/ting,odyvarv/ting-1,odyvarv/ting-1,VitSalis/ting,dionyziz/ting,sirodoht/ting,dionyziz/ting,VitSalis/ting,mbalamat/ting,mbalamat/ting,gtklocker/ting