The grid (core) · console.warn

tree.path threw; the affected rows were dropped from the hierarchy.

Printed by The grid (core), prefixed [lattice], since 1.0.1.

Warnings reference › tree.path.throw

Identifier: tree.path.throw
Raised by: The grid (core)
Since: 1.0.1

What happened

The tree.path function threw for a row, so the grid has no place to put it and it is left out of the tree entirely - it is not at the root, it is simply not there.

The fix

The error is attached to the console line. path must return an array for every row.

Reference

Covered in full at the API reference.