Fixed error when image cannot be found locally

When an image cannot be found locally, no image object is instantiated.
However, the method tried to access a method of this object, resulting in
an error. Now, in this case an empty string is returned.

Change-Id: I5b10d278485b88af2ea15f7a48996f5cf7ba4a20
Merge "Fixed error when image cannot be found locally"