Error is shown when adding a play animation node to a state when the original play animation node has been disconnected

This also occurs in 4.13.2

1. Open a Blueprint ThirdPerson project in the editor
2. Open ThirdPerson_AnimBP asset
3. Focus the Default State Machine window
4. Double-Click on the JumpStart state
5. Disconnect the ThirdPersonJump_Start node from Final Animation Pose
6. Add a ThirdPerson_Jump node

Result: Error is shown on original animation node