Well. It's as it says.
You're out of memory. See if you're not trying to load a few 256mb textures.
This is what's confusing. I checked my textures and everything was a couple hundred kb (whole textures folder was 40mb). Made a new one recently where the entire textures and assets were around 6mb total and got the same problem. Keeps happening and being temperamental and once it happens the project simply won't open ever again.
Always get this message: something went horribly wrong and an unhandled exception has been caught. The editor will close now. Log was saved to error.log.