The monumentCheckIn method in firebase_social_repository.dart contains a static analysis warning due to an unused local variable (doc). When a user checks into a monument, the code creates a new post in Firestore but unnecessarily assigns the DocumentReference to a variable that is never used. This triggers a Dart analyzer warning (unused_local_variable), indicating code inefficiency and potential confusion for future contributors.

Steps to Reproduce:
Navigate to lib/data/repositories/firebase_social_repository.dart.

Locate the monumentCheckIn method.

Observe the line:

dart
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DocumentReference doc = await _database.collection("posts").add({ ... });
Run dart analyze or view the file in an IDE (e.g., VS Code).

Result: A warning is generated:

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The value of the local variable 'doc' isn't used.
Expected Behavior:
No static analysis warnings.

All declared variables are actively used in the code.

Actual Behavior:
A static analysis warning is raised due to the unused doc variable.

Impact:
Code Quality Degradation: Unused variables clutter the codebase and reduce readability.

Maintainability Issues: Future contributors may waste time investigating why the variable exists.

Technical Debt: Small warnings like this accumulate over time, making the code harder to audit.

Proposed Fix:
Remove the assignment of the unused doc variable and directly await the Firestore add operation:

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await _database.collection("posts").add({ ... });