"Illegal instruction: 4" after updating to Tahoe 26.4

I am a software developer. I updated to macos Tahoe 26.4 and Xcode 26.3 yesterday (25 March 2026)
and now when I try to run the product I am developing I get "Illegal instruction: 4". 
I think the problem is occuring before my product's "main", which suggests the problem is with one 
of yesterday's updates from Apple. What do I do next ? 
I tried putting a session log here but it exceeded a 5000 character limit. 
I will try to find the additional text feature, also I have put the session transcript here 

I suspect it's a problem with one of yesterday's updates.