stopArc() during startArc() if an error occurs.
stopArc() during startArc() if an error occurs.

PiperOrigin-RevId: 341701321

PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs,PolymerLabs/arcs