setOutput
Sets this node's output to value's JSON form under T's serializer, or to a Content as it is, so a successor typed T reads it back, live and after a session reload. Can be called at most once per activation, and drops value if runNode already delegated output to a child with useAsOutput. Use it from a custom node for a typed value, since emitting that value directly fails the node.
Throws
if an output was already produced, or if called from a node {} body, whose return value is its output.