[5.x] Fix assets:generate-presets command stdout

[0kyn]

This PR fixes generate presets command stdout.

Running sail artisan statamic:assets:generate-presets
It adds an errors line even if there's no error

Generating presets for Medias...
 ┌ Generating cp_thumbnail_small_portrait for picture.png... ┐
 │ ████████████████████████████████████████████████████████████   │
 └───────────────────────────────────────────────────── 1141/1141 ┘

 [✔] 1141 images generated for 163 assets.

  medium ................................................................ 163  
  medium2x .............................................................. 163  
  small ................................................................. 163  
  small2x ............................................................... 163  
  thumbnail ............................................................. 163  
  thumbnail2x ........................................................... 163  
  cp_thumbnail_small_portrait ............................................ 22  
  cp_thumbnail_small_landscape .......................................... 128  
  cp_thumbnail_small_square .............................................. 13  
  errors ....................................................................