Missing style of wms in legend

[qifeng-bai]

Describe the bug Legend is not displayed in legend

To Reproduce Steps to reproduce the behavior:

1. Move map to Tasmania
2. Click on 'Tools->Points to Grid'
3. Choose area: current context
4. Choose species: Eucalyptus gunnii
5. Grid cell size: 0.1
6. Tick all three options
7. Change to 3X3
8. Click next

The tool will run and display result However, the bottom left legend panel shows an invalid graph - due to missing geoserver style in its link