This pull request partially reverts changes from e16c3b4a4421 Original motivation for this assert was described with "A WorkProduct without a saved file is useless" which was true at the time but now it is possible to have work products with other types of files (llvm-ir, asm, etc) and there are bugreports for this failure: For example: https://github.com/rust-lang/rust/issues/123695 Fixes https://github.com/rust-lang/rust/issues/123234 Now existing `assert` and `.unwrap_or_else` are unified into a single check that emits slightly more user friendly error message if an object files was meant to be produced but it's missing