[nullsafe] do not crash when java_class_info is empty
[nullsafe] do not crash when java_class_info is empty

Summary:
This sometimes happens and brings down all of infer with it. Just log
the error instead.

Fixes https://github.com/facebook/infer/issues/1338

Reviewed By: ezgicicek

Differential Revision: D25637821

fbshipit-source-id: 681207813

jvillard/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,jvillard/infer,jvillard/infer,jvillard/infer,jvillard/infer,jvillard/infer,jvillard/infer,facebook/infer,facebook/infer