Fail early and provide better message on error loading config

git-svn-id: https://valelab.ucsf.edu/svn/micromanager2/trunk@14626 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd
Prevent super-wide error message dialogs

git-svn-id: https://valelab.ucsf.edu/svn/micromanager2/trunk@14627 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd