[flang-commits] [flang] [flang] Fix seg fault `CodeGenAction::executeAction()` (PR #78269)

[Kareem Ergawy via flang-commits]

ergawy wrote:

> Thanks!
> 
> It would be good to add a diagnostic and a test - perhaps trying compiling a "broken" MLIR file?

Done! 

https://github.com/llvm/llvm-project/pull/78269