Handle null returned from getParentFile

[dgault]

This PR is in conjunction with ome/ome-common-java#12

To test:

• Ensure all builds and tests are green

[mtbc]

Ready for review?

[sbesson]

With ome/ome-common-java#12 requiring some work to minimize the impact on client code, would using the return value of Location.getParent() to perform the non-null check be a possibility to address this issue in the interim?

[sbesson]

Closing for now. Requires a bit more investigation to address this issue while minimizing the impact on the code/readers.