Hello again lucid ,
Thanks for your quick reply with the previous issue.
Taking my attempt to switch to the the latest versions of Spriter and it's Plugin a bit further, I opened a C2 project containing two non-atlas scml object, which were imported with a previous version of the plugin.
With C2 r225, the expected error message popped up when opening the project with the latest version of the plugin (yesterday's).
With C2 r239, oddly enough, the C2 project opened and was previewed with no errors, so long as I didn't try to change either scml object to an atlas version, or use C2's image editor on either one.
With either version of C2, Chrome displayed error messages if a scml object was either changed to an atlas version, or even if C2's image editor was used to give the scml object dimensions of more than 0X0px.
I just worked it out, and apologize for not trying this before posting.
For the benefit of anyone else who encounters this problem:
1. I should have corrected the scml-object's image for ALL scml objects after updating the plugin, and not just the one I was going to change to the atlas version.
2. After fixing the images in C2, the project must be saved, closed, and opened again before trying to preview.