Bug: When using the Brush tool, "incomplete brush" error occurs

**Describe the bug**
When using the Brush tool in Label Studio v1.17.0, an error occurs during or after drawing. Sometimes the brush region becomes unusable, and a browser console error is thrown related to a BrushRegionModel being accessed after removal from the state tree.

**To Reproduce**
Steps to reproduce the behavior:
1. Open a labeling task with the Brush tool.
2. Press the left mouse button to begin drawing a brush region.
3. Release the left mouse button, browser console shows MobX-State-Tree errors about accessing a disposed BrushRegionModel.
4. Press the left mouse button outside the region to drawing new brush region, The UI throws an "incomplete brush" error until release the left mouse button.

**Expected behavior**
Release the left mouse button to end the current brush region, press the left mouse button again to start a new brush region.

**Screenshots**


**Environment (please complete the following information):**
- OS: MacOS 15.4
- Browser: Chrome
- Label Studio Version v1.17.0