message: make sure the playbackRate is never 0
diff: @@ -6,6 +6,7 @@ import { Clock } from "../../core/clock/Clock";
  import { Cents, Positive, Seconds, Time } from "../../core/type/Units";
  import { ToneBufferSource } from "./ToneBufferSource";
  import { intervalToFrequencyRatio } from "../../core/type/Conversions";
  +import { assertRange } from "../../core/util/Debug";
  interface GrainPlayerOptions extends SourceOptions {
  onload: () => void;
  @@ -235,6 +236,7 @@ export class GrainPlayer extends Source<GrainPlayerOptions> {
  return this._playbackRate;
  }
  set playbackRate(rate) {
  + assertRange(rate, 0.001);
  this._playbackRate = rate;
  this.grainSize = this._grainSize;
  }
  