New project is created (empty) locally and on server when storage limit is reached

Description
When attempting to create a new project in a workspace that has reached its storage quota, the QGIS plugin still creates a new empty project both locally (folder) and on the server (project stub). Expected behavior is to show a clear error and not create any project nor local artifacts.

Environment
Staging

Application (+ app version, build, operating system)

• QGIS version: 3.40.5-Bratislava
• Plugin version: 2025.4.1
• macOS: Sequoia 15.6

Steps to reproduce

1. In the Mergin Maps QGIS plugin, switch to the workspace "storage_limit".
2. Click "Create New Project" and choose New basic QGIS project.
3. Complete the wizard to create the project in the "storage_limit" workspace.
4. Observe the outcome.

Actual results

• Server responds with an error "You have reached a data limit (StorageLimitHit)"
• A new empty project is still created on the server.
• A local empty project folder is also created.
• The wizard indicates failure, but residual artifacts remain both locally and on server.

Expected results

• No project is created on the server and no local folder/artifacts remain.

Screenshots or logs

Conclusion
Created by GitHub Copilot and supervised by a human test analyst.

Start by reproducing the failure with the QGIS plugin's Create New Project wizard in the storage_limit workspace and trace the local and server project-creation steps. Done means a StorageLimitHit error leaves neither a server project stub nor a local project folder or other artifacts.