lsusb -v fails when pavucontrol (PulseAudio Volume Control) is open and there is a Dell AC511 soundbar attached

[Veron Rado]

If pavucontrol "PulseAudio Volume Control" is open it causes 'sudo lsusb -v' to fail if there is a Dell AC511 soundbar attached via USB.

The error message:
> $ sudo lsusb -v
>
> ----[ snip ]----
>
> Bus 001 Device 002: ID 413c:a503 Dell Computer Corp.
> lsusb: gconv.c:74: __gconv: Assertion `outbuf != NULL && *outbuf != NULL' failed.
> Aborted

lsusb -v by device ID:
> $ sudo lsusb -v -d 413c:a503
>
> Bus 001 Device 002: ID 413c:a503 Dell Computer Corp.
> lsusb: gconv.c:74: __gconv: Assertion `outbuf != NULL && *outbuf != NULL' failed.
> Aborted

The bug goes away when "PulseAudio Volume Control" is closed.

Ubuntu 17.10
Linux 4.13.0-32-generic x86_64
pavucontrol version 3.0-3.1
lsusb (usbutils) 007