Handle edge cases in serialization

**Problem**
When working with helpers, the error messages could be more descriptive.

**Suggestion**
Improve error handling and add detailed error messages.

**Context**
This would help with debugging and maintenance.

No file or test is named. Start by locating the serialization helpers and reproducing the current error cases described in the issue, then inspect existing tests around those helpers. Done means the relevant edge cases are covered and failures report more descriptive errors.

Written by the indexing model from the issue text.