Specifying non-existing working directory for a build step isn't handled properly

[Panzerschrek]

How to reproduce

Just specify non-existing directory as working directory for a build step. Build starts, but no warning/error is displayed if this directory doesn't exist and the build step is executed using current process working directory.

This happens at least on GNU/Linux.

My build configuration:

Command: u.._build_system
Arguments: build -v
Working directory: non_existing_directory

Build output:

2025-04-10 19:05:50: Running steps for project New Name...
2025-04-10 19:05:50: Starting u.._build_system build -v
2025-04-10 19:05:50: Working Dir non_existing_directory/
Bürokratie - the Ü build system!
Build system executable directory path: "/home/panzerschrek/Projects/U-Sprache/other/install/bin"
Compiler executable path: "/home/panzerschrek/Projects/U-Sprache/other/install/bin/u.._compiler1"
Build project in "/home/panzerschrek/Projects/eepp" using build directory "/home/panzerschrek/Projects/eepp/build/release"
No dependency file "/home/panzerschrek/Projects/eepp/build/ustlib.o.d" - perform the build.
Building "/home/panzerschrek/Projects/eepp/build/ustlib.o".
Can not get modification time for "/home/panzerschrek/Projects/eepp/build.u" - file does not exist?
Failed to load/build the build script shared library.
The process "u.._build_system" exited with errors.
2025-04-10 19:05:51: Elapsed Time: 1.41s.
2025-04-10 19:05:51: Build run with errors

u.._build_system sees /home/panzerschrek/Projects/eepp as its working directory, which happens to be the directory from which I run ecode.

Expected behavior

Some warning or error is displayed if specified working directory doesn't exist. It's necessary to do so, since otherwise it may be tricky to identify why a particular build fails.

[SpartanJ]

I agree that user should be warned, but build must continue anyways because working directory can be wrong and still build just fine, for example if you used an absolute path for the command and the working directory wasn't a factor to successfully build. So I added a warning when printing the working dir if it cannot be found. It should be visible enough:

Thanks for the suggestion!