asset_path_not_string

Asset paths are required to be file paths (strings).

The analyzer produces this diagnostic when an asset map contains a path value that isn't a string.

The following code produces this diagnostic because the asset map contains a path value which is a list:

name: example
flutter:
  assets:
    - path: [one, two, three]
      flavors:
      - premium

Change the asset map so that it contains a path value which is a string (a valid POSIX-style file path):

name: example
flutter:
  assets:
    - path: image.gif
      flavors:
      - premium