Hi, nice to hear that you are still using it, it would be great if you could show some of your work at some point!
This looks like either the *.json file or the *.png file is unable to be read for some reason. Are the files located on the same server? Are they on another server? Check the 'network' tab (perhaps after a reload so you capture the requests.) This may show you the request that failed and a little more information about what is going on.
Check the atlas file first line is there anything interesting about the path to the *.png file?
Did the export include more than _one_ png file?
Recently I got cdn style loading of png, atlas, json working (using a different server for these files vs the the server where the game loads from.) The one change I had to do was update the first line of the atlas file to use the same cdn path. Though if you are not doing cdn, this will not be the issue.
If you can't fix it, you can find me on the Construct Discord server and send me the project via DM and I can take a look.