[PM-30444] Handle missing Braintree customer in GetPaymentMethodQuery

[amorask-bitwarden]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-30444

📔 Objective

In the GetPaymentMethodQuery, handle the Braintree.Exceptions.NotFoundException for an invalid Braintree Customer ID.

📸 Screenshots

Screen.Recording.2026-01-26.at.12.57.42.PM.mov

⏰ Reminders before review

• Contributor guidelines followed
• All formatters and local linters executed and passed
• Written new unit and / or integration tests where applicable
• Protected functional changes with optionality (feature flags)
• Used internationalization (i18n) for all UI strings
• CI builds passed
• Communicated to DevOps any deployment requirements
• Updated any necessary documentation (Confluence, contributing docs) or informed the documentation team

🦮 Reviewer guidelines

• 👍 (:+1:) or similar for great changes
• 📝 (:memo:) or ℹ️ (:information_source:) for notes or general info
• ❓ (:question:) for questions
• 🤔 (:thinking:) or 💭 (:thought_balloon:) for more open inquiry that's not quite a confirmed issue and could potentially benefit from discussion
• 🎨 (:art:) for suggestions / improvements
• ❌ (:x:) or ⚠️ (:warning:) for more significant problems or concerns needing attention
• 🌱 (:seedling:) or ♻️ (:recycle:) for future improvements or indications of technical debt
• ⛏ (:pick:) for minor or nitpick changes

[github-actions]

Checkmarx One – Scan Summary & Details – c27783d5-a1de-4d55-8dd5-19a9bee26bbf

Great job! No new security vulnerabilities introduced in this pull request

[codecov]

Codecov Report

❌ Patch coverage is 60.00000% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.09%. Comparing base (2a45880) to head (a6c4f52).

Files with missing lines	Patch %	Lines
...e/Billing/Payment/Queries/GetPaymentMethodQuery.cs	60.00%	5 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6899   +/-   ##
=======================================
  Coverage   56.08%   56.09%           
=======================================
  Files        1968     1968           
  Lines       86974    86986   +12     
  Branches     7748     7748           
=======================================
+ Hits        48783    48793   +10     
- Misses      36385    36387    +2     
  Partials     1806     1806           

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[sbrown-livefront]

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