only pass voxelset if it exists

bsb/placement/strategy.py

@@ -206,6 +206,8 @@ def queue(self, pool, chunk_size):
     def place(self, chunk, indicators):
         for indicator in indicators.values():
             cell_type = indicator.cell_type
+            # Pass the voxelset if it exists
+            voxels = getattr(p, "voxelset", None)
             # Guess total number, not chunk number, as entities bypass chunking.
-            n = sum(np.sum(indicator.guess(voxels=p.voxelset)) for p in self.partitions)
+            n = sum(np.sum(indicator.guess(voxels=voxels)) for p in self.partitions)
             self.scaffold.create_entities(cell_type, n)