Add ID conversion check in CharacterFactory

[glmdgrielson]

This should fix issue #536.

✅ Changes

• fix: Fix JSON having invalid/missing ID values.

🌄 Context

As per issue #536, Fari currently makes no checks on the imported JSON and accepts it without question.

🔒Checklist

• I tested my work on the feature environment

💅 Examples

• A test case has been added in CharacterFactory.test.tsx.