word-search: Remove unneeded exception case comment
word-search: Remove unneeded exception case comment

There is no mention of the value `-1` anywhere in the canonical data, so this comment line can be removed.

exercism/x-common,petertseng/x-common,jmluy/x-common,rpottsoh/x-common,rpottsoh/x-common,exercism/x-common,jmluy/x-common,petertseng/x-common,ErikSchierboom/x-common,jmluy/x-common,ErikSchierboom/x-common