So good and bad news, it's not exactly corrupted, but it's also not present... in other words, what you have contains 0 props and items, yet 242kb of data...
I suspect what's happened is at some point the game files have reset, which is backed up by the scene code you have- this is identical to the default for custom maps except a differing outer terrain- unless this is intentional, I'd have said the correct scene code was missing.
To summarise, I'm sorry to say but the file you uploaded is not usable as a map
As you also have been receiving an error when loading this file I also wonder if there's more to it, I'd suggest backing up your game files and running verify game cache through steam to reset everything to default. I didn't receive the same error when loading in. Hope this helps, and sorry again to be the bringer of bad news.