" then open a different patch. Open any CFG inside the different patch (recommended that you choose the CFG that has the same thing as the corrupted CFG). Once you open it, open the other patch with the error. There should still be a remaining tab of the functional CFG from the other patch. Now attempt to open the corrupted CFG. If the error pops up, just close it by clicking the X button on the top right. Now go to the other tab that has the non corrupted version of the same CFG, then press Save Current GSC. It's gonna replace the corrupted CFG with the functional version from the other patch. Now press that certain cfg again and you will no longer see that error, and you can proceed editing! This usually happens after zone editing.

You can actually do this if you just click on another tab of the same patch but it's better to open a different patch because it has the previous version of what you were working on, unless you didn't make a backup file...

Oh this works for GSC patches as well!