-e: see title
--works well in 2018.1b4, doesn't work with a trunk build (Version 2018.2.0a1 (43620cf10b35))
--not check on OSX yet

-repro:
--create new project
--open build settings
--select standalone
--click build
--navigate to some folder to build into but then cancel the system file dialog
--NOTICE an exception is thrown:
---"ArgumentException: The specified path is not of a legal form (empty)."