New to JobDSL, so please bear with me!

When loading files from the workspace using readFileInWorkspace() or streamFileInWorkspace(), a missing file will throw an IllegalStateException (debates on that probably not in scope...)

It would be very helpful to the end user to include the path to the missing file (I know because we spent a lot of time looking at the wrong section of our JobDSL code over the last couple of days).

FWIW, there's also a typo in the message...