Seems like your project files are corrupted. Are there many more errors like that in the console log? If only a few files got corrupted, you may be able to manually fix them.
If you have a C3P project, try renaming it to ZIP (make a backup copy first of course!)
Unzip the files and try opening those json files from the error messages. You can use online tools which will check JSON integrity, for example:
You can also email your project file to Construct support, maybe they will be able to help.