Remove fragile assert()

The sc_uhid_devices instance is initialized only when there is a UHID
keyboard.

The device message receiver assumed that it could not receive HID output
reports without a sc_uhid_devices instance (i.e. without a UHID
keyboard), but in practice, a UHID driver implementation on the device
may decide to send UHID output reports for mouse or for gamepads (and we
must just ignore them).

So remove the assert().

PR #5270 <#5270>

app/src/receiver.c

@@ -121,11 +121,6 @@ process_msg(struct sc_receiver *receiver, struct sc_device_msg *msg) {
                 }
             }
 
-            // This is a programming error to receive this message if there is
-            // no uhid_devices instance
-            assert(receiver->uhid_devices);
-
-            // Also check at runtime (do not trust the server)
             if (!receiver->uhid_devices) {
                 LOGE("Received unexpected HID output message");
                 sc_device_msg_destroy(msg);