Fixes panic error on decl_to_type_info.

[esdrubal]

Description

Doing an unwrap without checking if the value was none was causing a panic. Fixed by throwing an error so we can also see the previous errors.

Fixes #6330

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.

[codspeed-hq]

CodSpeed Performance Report

Merging #6552 will not alter performance

_{Comparing esdrubal/panic_in_decl_to_type_info (4b4019b) with master (a073a95)}

Summary

✅ 22 untouched benchmarks