Try harder to show exceptions while loading a StoreHandler.
Try harder to show exceptions while loading a StoreHandler.

Try to ensure that the caught exception while importing a StoreHandler module
is exactly the exception which relates to it. This specifically unhides an
exception caught when the module being loaded throws an exception because a
module it loads does not exist.

Fixes: https://github.com/certain/certain/issues/2

certain/certain,certain/certain