[2019] Wrong shader file decoded size?

We're looking into this at the moment! I'll keep you updated.
Edit 1: We've created a potential fix and we're just about to test it. If that goes well we will push it to the live realm.
Edit 2: The test went well. New patch incoming!
Edit 3: The new Steam patch is now available. Stand alone patch still coming.
Edit 4: You should now also be able to patch on the stand alone client.
Edit 5: Please ignore edit 4 and forgive me. Still waiting on the stand alone client patch.
Edit 6: The stand alone patch is now live. If you're receiving the "In source code file:" error on Steam can you please let us know when this happens?
Edit 7: The shader error appears to be fixed now but people are still experiencing the "In source code file:" on both the Steam and stand alone clients. We're investigating this now. Thank you for your reports.
Edit 8: We're opening the queues while we investigate this. It seems that you can click past the error but we will still need to resolve it.

Thanks. I've let the team know.

That does help! Thank you.

If you'd like to but I don't think it will help.

This one is likely to be different. Maybe check if you have a firewall that might be preventing you from patching.

Every second that you're alive marks the end of the world as you know it and brings forth a new one. Change is constant. LIVE IN THE NOW!

I have no idea what that book is I'm just talking sh*t because I'm really tired but also in a good mood.

Yes, you're still waiting. Please see my first comment for updates.

If you downloaded the torrent and moved your content.ggpk folder you'll still need to download a patch. Please try downloading it and see if that corrects the error.