Accept non-instanciated nodes for better developer experience

packages/superdough/helpers.mjs

@@ -555,6 +555,8 @@ export const getFrequencyFromValue = (value, defaultNote = 36) => {
 };
 
 export const releaseAudioNode = (node) => {
+  if (node == null) return;
+
   // check we received an AudioNode
   if (!(node instanceof AudioNode)) {
     throw new Error('releaseAudioNode can only release an AudioNode');

packages/superdough/synth.mjs

@@ -343,7 +343,7 @@ export function registerSynthSounds() {
         ac,
         () => {
           releaseAudioNode(o);
-          lfo && releaseAudioNode(lfo);
+          releaseAudioNode(lfo);
           onended();
           fm?.stop();
           vibratoOscillator?.stop();