fix: #323 TypeError when list json with lottie

[wasabeef]

What does this change?

Fixes #323

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

• Make sure to open a GitHub issue as a bug/feature request before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
  • Ensure the tests (melos unit:test-script)
  • Ensure the analyzer and formatter pass (melos run format to automatically apply formatting)
• Appropriate docs were updated (if necessary)