This is a new behavior, occuring (I think) since 1.0.3-alpha1:
An error message is shown on first "Commit" action, After clicking commit action second time, no error is shown, dialog closes, component is persisted & works fine.

How to reproduce:

1. Open component with a celumLinkField
2. Pick a Celum asset through (paged) picker dialog
3. Click Save ("commit") in component dialog
-> Error is thrown, error message is displayed
4. Click Save again, no error is thrown

Find the error log attached: CELUM-46.log
Also a screenshot after first "Commit" action. Notice that in this situation no preview for the asset is shown in the celumLinkField: