7.0.X, 7.1.X, Master
0.) Use the latest master bundle
1.) Make sure the Adaptive Media plugin is deployed. When the system has started please verify it in Control Panel → Configuration → Adaptive Media.
2.) Create a new site and enable local Staging.
3.) Go to Content → Web Content, here create a basic web content and from alloy editor select and image and publish it.
4.) Make a Staging publication.
Checkpoint: Everything should work as expected.
5.) Go back to Content → Web Content, edit the article created in step 3 and change the image to source view. Manually delete the fileentryid value (you should see ‘data-fileentryid=""’) and publish it.
Checkpoint: It is a bit strange that the article can be published without any warning messages. This isn't the most relevant part of the use case.
6.) Make the Staging publication.
Result: You will get a java.lang.NumberFormatException: For input string: "" on the UI and detailed log it attached to the LPP.
master @ commit (ff37027c5444b07f828061372960853cdb22199c) reproduced