Environment variables inside cwd

[shahamran]

Hi, and thank you for this amazing project!

I'm trying to define a layout which I'll share with my teammates, and it includes paths that contain env variables that may be different between users. For example, I want to do something like:

layout {
  pane name="profiling" cwd="/somewhere/$USER/profiling"
}

where $USER is such environment variable.
When I open zellij with such layout, it silently falls back to current dir.

I actually consider the current behavior a bug. IMO it should either fail with an error, or do the right thing. (I realize that "the right thing" here is complicated because of cwd composition.)
Adding a section on "what happens if a path is invalid", and "what paths are valid" to the creating-a-layout doc page will also be helpful.

Thanks again!

[shahamran]

I created a PR that adds support for this.

Also, I take back what I said about this being a bug. It's clearly marked as an error in the log file. I guess it can be more clear where the log file is located.