Add additional guards to HTML5 AudioSource if buffer is null

lime/_backend/html5/HTML5AudioSource.hx

@@ -85,7 +85,7 @@ class HTML5AudioSource {
 		#if howlerjs
 		
 		playing = false;
-		parent.buffer.__srcHowl.pause (id);
+		if (parent.buffer != null) parent.buffer.__srcHowl.pause (id);
 		
 		#end
 		
@@ -97,7 +97,7 @@ class HTML5AudioSource {
 		#if howlerjs
 		
 		playing = false;
-		parent.buffer.__srcHowl.stop (id);
+		if (parent.buffer != null) parent.buffer.__srcHowl.stop (id);
 		
 		#end
 		
@@ -160,7 +160,7 @@ class HTML5AudioSource {
 			
 			return getLength ();
 			
-		} else {
+		} else if (parent.buffer != null) {
 			
 			var time = Std.int (parent.buffer.__srcHowl.seek (id) * 1000) - parent.offset;
 			if (time < 0) return 0;
@@ -168,12 +168,10 @@ class HTML5AudioSource {
 			
 		}
 		
-		#else
+		#end
 		
 		return 0;
 		
-		#end
-		
 	}
 	
 	
@@ -231,14 +229,16 @@ class HTML5AudioSource {
 		
 		#if howlerjs
 		
-		return Std.int (parent.buffer.__srcHowl.duration () * 1000);
-		
-		#else
-		
-		return 0;
+		if (parent.buffer != null) {
+			
+			return Std.int (parent.buffer.__srcHowl.duration () * 1000);
+			
+		}
 		
 		#end
 		
+		return 0;
+		
 	}