<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Work on this issue](https://contributors.gitlab.com/manage-issue?action=work&projectId=278964&issueIid=561956) </details> <!--IssueSummary end--> ##Background We've observed errors in Sentry where GraphQL queries resolve successfully but return empty objects, bypassing UI error handling. The backend schema allows mergeRequests: null (null: true), but we need to understand when and why this occurs. Spike Goals ##This spike focuses on steps 1 and 2 from [the investigation plan](https://gitlab.com/gitlab-org/gitlab/-/issues/554041#note_2619429668): 1. Identify null scenarios Investigate the resolver code to understand when the backend returns null for mergeRequests Document all code paths that lead to null responses Identify the conditions/triggers for each scenario 2. Evaluate appropriateness For each identified scenario, determine whether null is the appropriate response Assess which scenarios should return proper GraphQL errors instead Document recommendations for each case ## Expected Deliverables Documentation of all null response scenarios and their triggers Analysis of which scenarios are appropriate vs should error Recommendations for backend changes (if any) Clear guidance for frontend null handling requirements