Does not print pokemon, choice: unown-c about pokesay

[tmck-code]

I've merged a PR that fixes this, thanks for submitting the issue!

When converting the pokesprite pngs -> cowfiles, the img2xterm tool fails to convert some of them and results in empty data. I now skip over these, and I've double-checked that the offenders have been removed

• before

   ☯ ~/d/p/build for f in $(find -iname unown-l*) ; do ls -alh $f && cat $f ; done
   
   -rw-r--r-- 1 freman freman 0 Mar 16 22:22 ./cows/pokemon-gen7x/regular/unown-l.cow
   -rw-r--r-- 1 freman freman 0 Mar 16 22:22 ./cows/pokemon-gen7x/regular/right/unown-l.cow
   -rw-r--r-- 1 freman freman 1.3K Mar 16 22:22 ./cows/pokemon-gen7x/shiny/unown-l.cow
   -rw-r--r-- 1 freman freman 1.2K Mar 16 22:22 ./cows/pokemon-gen7x/shiny/right/unown-l.cow
   -rw-r--r-- 1 freman freman 0 Mar 16 22:22 ./cows/pokemon-gen8/regular/unown-l.cow
   -rw-r--r-- 1 freman freman 1.3K Mar 16 22:22 ./cows/pokemon-gen8/shiny/unown-l.cow
  

• after

   ☯ ~/d/p/build for f in $(find -iname unown-l*) ; do ls -alh $f && cat $f ; done
  
  -rw-r--r-- 1 freman freman 1.3K Mar 16 22:30 ./cows/pokemon-gen7x/shiny/unown-l.cow
  -rw-r--r-- 1 freman freman 1.2K Mar 16 22:30 ./cows/pokemon-gen7x/shiny/right/unown-l.cow
  -rw-r--r-- 1 freman freman 1.3K Mar 16 22:30 ./cows/pokemon-gen8/shiny/unown-l.cow
  

[tmck-code]

Thanks for opening an issue @madsaune! I'll look into this