Hi Anna,
Yes I have update all the plugins. At this moment I have:
WC VENDORS 1.9.11
WC VENDORS PRO 1.4.3
WOOCOMMERCE 3.0.6
I checked this error with other vendor user and the error not appears.
And yes I deleted one order… so as you say could be the system… But I can leave this error like this… because it appears in a trial version user vendor of us 🙂 (not an real vendor)
So I think I will not deleted any order for the reals vendors at this way…