Describe the bug, including details regarding any error messages, version, and platform.

Yep, it's a bit obscure, this one 😅

Arrow 17.0.0

Steps:

1. Create a FixedSizeListVector (FSLV), it initialises with a ZeroVector for its elements.
2. Add it to a dense-union through DUV.addVector
3. That method transfers the empty FSLV through DUV.addVector but, in doing so, it creates a NullVector in the new vector rather than a ZeroVector.
4. Trying to set the element vector using FSLV.addOrGetVector throws SchemaChangeRuntimeException, because it explicitly checks for ZeroVector.

Will submit a test case and a fix shortly in a PR 🙂

Component(s)

Java