fix: "MongoServerError: The _id cannot be changed" when updating users

[andypols]

Summary

Updating a user (e.g., adding a GitHub username) currently fails with a MongoDB server exception. The issue arises because the user object already includes an _id, and the update attempt tries to overwrite it:

MongoServerError: The _id field cannot be changed

Fix

• Removes the _id property from the user object before updating.
• Performs an update by _id if one exists.
• If no _id is present, inserts a new user with a no-op filter ({ username: user.username }).

[netlify]

✅ Deploy Preview for endearing-brigadeiros-63f9d0 canceled.

Name	Link
🔨 Latest commit	050e70f
🔍 Latest deploy log	https://app.netlify.com/projects/endearing-brigadeiros-63f9d0/deploys/68d6c2e744bc470008aa04d8

[codecov]

Codecov Report

❌ Patch coverage is 25.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.01%. Comparing base (32bfc70) to head (050e70f).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/db/mongo/users.ts	25.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1230      +/-   ##
==========================================
- Coverage   84.06%   84.01%   -0.06%     
==========================================
  Files          68       68              
  Lines        2944     2947       +3     
  Branches      373      374       +1     
==========================================
+ Hits         2475     2476       +1     
- Misses        409      411       +2     
  Partials       60       60              

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[kriswest]

LGTM

Are similar changes needed in any of the other dB clients?

[andypols]

@kriswest I did look for other mongo updates, but they all look good.