Fix ObjectDoesNotExist using invalid keyword argument

[preeeetham]

Proposed change

Resolves #3521

This PR fixes ObjectDoesNotExist(msg=...) which causes TypeError instead of the intended exception. Django's ObjectDoesNotExist does not accept keyword arguments:

>>> from django.core.exceptions import ObjectDoesNotExist
>>> raise ObjectDoesNotExist(msg='test')
TypeError: ObjectDoesNotExist() takes no keyword arguments

This means error handling was completely broken for these code paths - users would see TypeError instead of proper "not found" messages.

Changes

• Replace all 11 instances of ObjectDoesNotExist(msg=...) with positional arguments
• Add ASSIGNEE_NOT_FOUND_MSG constant to follow linter rules (EM101, TRY003)
• Use variable for f-string message to satisfy EM102 rule

Before (broken)	After (fixed)
ObjectDoesNotExist(msg=MODULE_NOT_FOUND_MSG)	ObjectDoesNotExist(MODULE_NOT_FOUND_MSG)
ObjectDoesNotExist(msg="Assignee not found.")	ObjectDoesNotExist(ASSIGNEE_NOT_FOUND_MSG)
ObjectDoesNotExist(msg=ISSUE_NOT_FOUND_MSG)	ObjectDoesNotExist(ISSUE_NOT_FOUND_MSG)

Checklist

• Required: I followed the contributing workflow
• Required: I verified that my code works as intended and resolves the issue as described
• Required: I ran make check-test locally: all warnings addressed, tests passed
• I used AI for code, documentation, tests, or communication related to this PR

[coderabbitai]

Summary by CodeRabbit

• Refactor

  • Improved consistency in error message handling within the mentorship backend.

• Chores

  • Internal code standardization and maintenance.

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Walkthrough

This PR fixes broken error handling in the mentorship module mutations by correcting ObjectDoesNotExist exception instantiation. It introduces centralized message constants for not-found scenarios and replaces invalid keyword argument usage with positional arguments, ensuring proper exception raising and GraphQL error handling.

Changes

Cohort / File(s)	Summary
Error Handling and Message Constants backend/apps/mentorship/api/internal/mutations/module.py	Introduced ASSIGNEE_NOT_FOUND_MSG, ISSUE_NOT_FOUND_MSG, and MODULE_NOT_FOUND_MSG constants. Replaced 11 instances of ObjectDoesNotExist(msg=...) with positional argument syntax ObjectDoesNotExist(...). Replaced hard-coded error strings with the new constants throughout the module.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• Refactor: duplicate 'module not found' message #3218 — Both PRs modify the same module file to centralize and replace inline not-found error messages with shared constants.

Suggested labels

backend

Suggested reviewers

• arkid15r
• kasya

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: fixing ObjectDoesNotExist calls that incorrectly use a keyword argument instead of positional arguments.
Description check	✅ Passed	The description is directly related to the changeset, explaining the bug, the fix applied, and the specific changes made to resolve issue #3521.
Linked Issues check	✅ Passed	The PR fully addresses issue #3521 by fixing all 11 instances of ObjectDoesNotExist with keyword arguments, adding the ASSIGNEE_NOT_FOUND_MSG constant, and ensuring linter compliance.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the ObjectDoesNotExist keyword argument issue in module.py; no unrelated modifications are present.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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[arkid15r]

Looks good, thank you!

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.48%. Comparing base (0299256) to head (3df1348).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3534   +/-   ##
=======================================
  Coverage   85.48%   85.48%           
=======================================
  Files         461      461           
  Lines       14240    14240           
  Branches     1896     1896           
=======================================
  Hits        12173    12173           
  Misses       1688     1688           
  Partials      379      379           

Flag	Coverage Δ
backend	84.48% <ø> (ø)
frontend	88.26% <ø> (ø)

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