Error on exit using sound library

Running the code at: Processing Reference: SoundFile Example
I got the following error when exit from sketch:

ERROR: /node/free: Node 1 not found
ERROR: /node/free: Node 3 not found
ERROR: /node/free: Node 2 not found
ERROR: /node/free: Node 4 not found

Does anyone know how to solve the problem ?
Thanks.
p.s. same error with processing 3.3.5 / windows 10 and processing 3.3.6 / windows 7.