spring-invalid

A springBones chain that is wrong whatever the rig is: it gives both joints and root/tip, gives neither, gives a tip without a root, or lists no bones; or one of its numbers is outside its range or not finite (stiffness 0..100000, damping 0..1000, radius 0..10, a gravity or tail entry). Bones the rig lacks, a tip that is not below its root, and a bone in two chains are found at load: spring-bone-unknown and spring-chain-bad, runtime codes (docs/RUNTIME-CODES.md).