Try block for check before usb_midi setup during init

Co-authored-by: Dan Halbert <[email protected]>

Author: fivesixzero

adafruit_macropad.py

@@ -256,15 +256,16 @@ def _keys_and_pixels(
         self._mouse = None
 
         # Define MIDI:
-        if len(usb_midi.ports) == 2:
+        try:
             self._midi = adafruit_midi.MIDI(
                 midi_in=usb_midi.ports[0],
                 # MIDI uses channels 1-16. CircuitPython uses 0-15. Ergo -1.
                 in_channel=midi_in_channel - 1,
                 midi_out=usb_midi.ports[1],
                 out_channel=midi_out_channel - 1,
             )
-        else:
+        except IndexError:
+            # No MIDI ports available.
             self._midi = None
 
     Keycode = Keycode