Map Viewer crashes with AttributeError: 'x1' missing on Blender 4.2

Blender version: 4.2 LTS BlenderGIS version: 2.2.15 OS: macOS (Apple Silicon / Intel)

Steps to reproduce:

1. Enable BlenderGIS
2. Go to GIS → Web geodata → Basemap / Map Viewer
3. Start Map Viewer in 3D Viewport
4. Click / interact with viewport

Expected result: Map viewer should allow selecting area

Actual result: Crash with traceback:

AttributeError: 'VIEW3D_OT_map_viewer' object has no attribute 'x1'

File: operators/view3d_mapviewer.py line 792

Notes: Seems related to missing initialization of x1/y1 in modal operator. Possibly related to Blender 4.x API changes for modal events.