"Reroute connection" example: User-created key-points break key-point movement

[JannikGM]

https://rete.js.org/#/examples/reroute
The original 2 key-points are moveable by the user, however movement stops working after manually creating a key-point.

Steps to reproduce:

• Open https://rete.js.org/#/examples/reroute
• Click and hold + drag each of the 2 key-points to see that everything works
• Click the upper key-point to remove it
• Click and hold + drag on the remaining key-point to see that it still works
• Click on the (now reshaped) upper connection to insert a key-point
• Click and hold + drag each of the 2 key-points to see that:
  1. The new key-point does not move anymore
  2. The old key-point does not move anymore

Tested in recent Firefox and Chrome.