Are you using a Handle component inside a component which is not present inside a CustomNode component? The error is indicating towards that
#Error="Handle: No node id found"
uncut lotus
urban smelt
The original solution was working (without errors). The refactored solution has changed nothing in GraphControllerSpecific nor GraphViewSpecific. CustomNodes.jsx was only changed in the sense that it provided an id to the ReactFlow component. This was necessary to ensure the panes did no use the same variables. For the rest, mainly the hierarchy of the components is diffferent between refactored and original solution and the fact that we now have two react providers for an independent side by side view. So to answer your question, I believe that is not the problem since the error points to a Handle in CustomNodes.jsx