const -> let

src/animation/AnimationMixer.js

@@ -521,8 +521,8 @@ AnimationMixer.prototype = Object.assign( Object.create( EventDispatcher.prototy
 
 		const clipUuid = clipObject !== null ? clipObject.uuid : clip;
 
-		const actionsForClip = this._actionsByClip[ clipUuid ],
-			prototypeAction = null;
+		const actionsForClip = this._actionsByClip[ clipUuid ];
+		let	prototypeAction = null;
 
 		if ( blendMode === undefined ) {