Handle edge cases in encryption

**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.

The issue names no files, tests, or entry points. Start by locating the helper encryption and error-handling paths, then identify the edge cases and define the expected descriptive messages before adding coverage for them.

Written by the indexing model from the issue text.