Fire Behaviour Calculator: Feedback on errors

**As a** *Fire Behaviour Analyst* **I want** *to have a detailed error message* **So That** *I can take appropriate action*

**Additional Context**
- When values critical to fire behaviour calculations are missing, the error status will simply report as "Error". So if, for example, the BUI is not present, a station will report with status "Error". This leave the user with no clear path forward in resolving the issue. If the user knew it was the BUI field that was missing, the user could follow up with personnel responsible for the weather station in question re. BUI not being reported.

**Acceptance Criteria**
- [ ] Given I have selected a valid weather station, date and fuel type, When there is an error in calculating values due to missing weather station values, Then I expect to understand why that error occurred.

No file, test, or entry point is named in the issue. Start by tracing the Fire Behaviour Calculator’s calculation path for missing weather-station values; done means a valid station, date, and fuel selection reports which required value is missing instead of only “Error,” with coverage for that case.

Written by the indexing model from the issue text.