fixed error while merging (#544)

* decoupled helpers method from p5 in helper.js and coupled them separately in app.js

* fixed build process bug in helpers.js

* addes saveSound import in app.js

src/app.js

@@ -21,6 +21,10 @@ import {
   interleave,
   writeUTFBytes,
   safeBufferSize,
+
+  saveSound
+
+
 } from './helpers';
 p5.prototype.sampleRate = sampleRate;
 p5.prototype.freqToMidi = freqToMidi;

src/helpers.js

@@ -344,7 +344,7 @@ function safeBufferSize(idealBufferSize) {
  *  @param  {String} fileName      name of the resulting .wav file.
  */
 // add to p5.prototype as this is used by the p5 `save()` method.
-export function saveSound(soundFile, fileName) {
+function saveSound(soundFile, fileName) {
   const dataView = convertToWav(soundFile.buffer);
   p5.prototype.writeFile([dataView], fileName, 'wav');
 }