fix: crash when importing subscriptions list with invalid avatars

[bodaciousbiscuits]

Solves issue of subscription list not loading when channels have old/invalid avatars.

See issue below:

video_2024-04-17_17-00-22.mp4

[bodaciousbiscuits]

While debugging the problem, the null pointer showed up in the logs:

04-17 07:51:48.227 19814  4443 E kotlinx.coroutines.StandaloneCoroutine: kotlinx.serialization.json.internal.JsonDecodingException: Unexpected JSON token at offset 27191: Expected string literal but 'null' literal was found at path: $[111].avatar
04-17 07:51:48.227 19814  4443 E kotlinx.coroutines.StandaloneCoroutine: Use 'coerceInputValues = true' in 'Json {}' builder to coerce nulls if property has a default value.
04-17 07:51:48.227 19814  4443 E kotlinx.coroutines.StandaloneCoroutine: JSON input: .....ame":"Channel","avatar":null,"verified":true},{"url":".....

[Bnyro]

Thanks 👍