ID 75638 - Clearer error messages for ExrCombine failures

Problem summary
When merging different EXR files into one, ExrCombine can fail for different reasons including the images to merge having different data windows. ExrCombine may crash with a segmentation fault when used outside Katana, or the render may fail within the application with a generic error message.

The errors provided should be clearer to specify what the issue is and help tracking down the cause.

Customer reported version
Katana 2.6v4

Customer reported platform
Linux

Steps to reproduce

1. Open the Secondary Images (AOVs) example project.

2. Add an additional RenderOutputDefine node into the node graph upstream of the Render node, set its type parameter to merge, select the three existing render passes as mergeOutputs, set locationType to file and specify a location for the file under locationSettings.renderLocation.

3. Right-click the Render node > Disk Render.

4. Observe that the ‘raw’ render outputs render correctly, but the render fails when attempting to write out the ‘merge’ output.

5. To write out a correct ‘merge’ output, the other outputs need to be of type color (set in RenderOutputDefine nodes) and can’t be tiled (uncheck driverParameters.tiled in ArnoldOutputChannelDefine nodes).