Primitives are given packages ...

[slarse]

If a node with a primitive type is matched to a node with a reference type, the reference type's package is often "transferred" to the primitive type. This is due to 3DM-merge having no concept of reference and primitive types, but we still want it to be possible to match reference types to primitive types, or we'll run into issues.

[slarse]

Solution: don't match primitive types with reference types.