fix: OPTIC-1248: Fixed error message that pops up when user checks heidi notifications checkbox at account settings

[mcanu]

PR fulfills these requirements

• Commit message(s) and PR title follows the format [fix|feat|ci|chore|doc]: TICKET-ID: Short description of change made ex. fix: DEV-XXXX: Removed inconsistent code usage causing intermittent errors
• Tests for the changes have been added/updated (for bug fixes/features)
• Docs have been added/updated (for bug fixes/features)
• Best efforts were made to ensure docs/code are concise and coherent (checked for spelling/grammatical errors, commented out code, debug logs etc.)
• Self-reviewed and ran all changes on a local instance (for bug fixes/features)

Change has impacts in these area(s)

(check all that apply)

• Product design
• Backend (Database)
• Backend (API)
• Frontend

Describe the reason for change

We were sending email as part of the newsletters subscription request, which raised an error here

What does this fix?

Error messaging popping up when clicking on Get the latest news & tips from Heidi checkbox.

Does this PR introduce a breaking change?

(check only one)

• Yes, and covered entirely by feature flag(s)
• Yes, and covered partially by feature flag(s)
• No
• Not sure (briefly explain the situation below)

What level of testing was included in the change?

(check all that apply)

• e2e
• integration
• unit

Which logical domain(s) does this change affect?

(for bug fixes/features, be as precise as possible. ex. Authentication, Annotation History, Review Stream etc.)

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✅ Deploy Preview for heartex-docs canceled.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.77%. Comparing base (86c907c) to head (a961ed1).
Report is 6 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #6698      +/-   ##
===========================================
- Coverage    76.77%   76.77%   -0.01%     
===========================================
  Files          170      170              
  Lines        13883    13883              
===========================================
- Hits         10659    10658       -1     
- Misses        3224     3225       +1     

Flag	Coverage Δ
pytests	76.77% <ø> (-0.01%)	⬇️

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