LCFS - Make Fuel type other mandatory when active

[airinggov]

Description:
For both Fuel supply and Export fuel schedules. Update the form validation logic to ensure that when 'Other' is selected from the 'Fuel type' dropdown, the 'Fuel type other' field becomes mandatory and cannot be left blank.

Wireframe:

Purpose and benefit to user:
Enforce accurate data entry by ensuring the 'Fuel type other' field is completed when 'Other' is selected, reducing incomplete or invalid submissions.

Acceptance Criteria:

1. When 'Other' is selected in the 'Fuel type' dropdown, the 'Fuel type other' field becomes active and is required.
2. Attempting to submit the form without completing the 'Fuel type other' field triggers an error message: "Fuel type other field is required"
3. The error message is displayed near the 'Fuel type other' field and follows the application's standard styling.
4. The form cannot be submitted until the 'Fuel type other' field is completed when 'Other' is selected.

Development Checklist:

• Update form logic to make 'Fuel type other' mandatory when active ('Fuel type', 'Other' is selected).
• Add an error message for empty 'Fuel type other' submissions.
• Test form behavior to confirm validation triggers only when 'Other' is selected.

Notes:

• Confirm error messaging with the design and content teams for consistency.