message: handling error case when url is passed into constructor
diff: @@ -71,7 +71,7 @@ define(["Tone/core/Tone", "Tone/core/Emitter", "Tone/type/Type", "Tone/shim/Audi
  }
  }
  } else if (Tone.isString(options.url)){
  - this.load(options.url, options.onload, options.onerror);
  + this.load(options.url).then(options.onload).catch(options.onerror)
  }
  };
  @@ -83,7 +83,9 @@ define(["Tone/core/Tone", "Tone/core/Emitter", "Tone/type/Type", "Tone/shim/Audi
  */
  Tone.Buffer.defaults = {
  "url" : undefined,
  - "reverse" : false
  + "reverse" : false,
  + "onload" : Tone.noOp,
  + "onerror" : Tone.noOp
  };
  /**
  