predicateTree.replace({operator:$or}) // any junction Operator
This throw unexpected error. It should throw error in this special case.
When creating fromEmpty the tree has one node (root) and no children, therefore no junction. Can only change junction after there are children nodes.
https://github.com/terary/gabby-query-protocol-lib/blob/9b468ee3a27ce6a88ab0d49b62cee0c179f0752e/src/PredicateFormulaEditor/PredicateFormulaEditor.ts#L104