[Bug] wxGUI: unclear error message in scatterplot with non-overlapping raster maps

[neteler]

Describe the bug

When attempting to draw an scatterplot, the plot is not shown:

To Reproduce
Steps to reproduce the behavior:

1. load two elevation maps from NC sample dataset:

• el_D792_6m@PERMANENT
• el_D783_6m@PERMANENT
  and select them in layer manager.

2. Go Analyze map (Display manager)
3. Create bivariate scatter plot
4. accept settings with OK
5. no plot shown but error in console:

Settings: unable to get value 'scatter:rasters:None'

System description (please complete the following information):

• Operating System: Fedora 35, wxPython: 4.0.7 with 4.1 patches
• GRASS GIS version: both 7.8.dev and 8.0.dev

System Info

GRASS version: 8.0.dev
Code revision: ff485ffdc                                                        
Build date: 2021-12-14                                                          
Build platform: x86_64-pc-linux-gnu                                             
GDAL: 3.3.2                                                                     
PROJ: 8.2.0                                                                     
GEOS: 3.9.2                                                                     
SQLite: 3.36.0                                                                  
Python: 3.10.1                                                                  
wxPython: 4.0.7                                                                 
Platform: Linux-5.15.6-200.fc35.x86_64-x86_64-with-glibc2.34

[petrasovaa]

This actually works for me.

[neteler]

This actually works for me.

When I select two maps in the Layers tab, then it works.
When I select two maps in the scatterplot dialog, it doesn't (with above error msg)... Can anyone confirm this?

[petrasovaa]

The 2 raster maps you used don't overlap, try e.g. elevation and elev_srtm_30m.

[neteler]

The 2 raster maps you used don't overlap,

Ops.

try e.g. elevation and elev_srtm_30m.

Yes, then it works. So, this would be a shy wish for a better user message.

I guess that it needs to be checked earlier than here:

grass/gui/wxpython/core/settings.py

Line 1068 in b62830b

"Settings: unable to get value '%s:%s:%s'\n" % (group, key, subkey),