Fix editor crash on audio preview

- Crash was due to getting -1 values when clamping [0, -1].
- This was happening due to 'max' being zero.
- If 'max' is zero we should return zero, as it can never be any other
value.

editor/audio_stream_preview.cpp

@@ -42,6 +42,10 @@ float AudioStreamPreview::get_max(float p_time, float p_time_next) const {
 	}
 
 	int max = preview.size() / 2;
+	if (max == 0) {
+		return 0;
+	}
+
 	int time_from = p_time / length * max;
 	int time_to = p_time_next / length * max;
 	time_from = CLAMP(time_from, 0, max - 1);
@@ -69,6 +73,10 @@ float AudioStreamPreview::get_min(float p_time, float p_time_next) const {
 	}
 
 	int max = preview.size() / 2;
+	if (max == 0) {
+		return 0;
+	}
+	
 	int time_from = p_time / length * max;
 	int time_to = p_time_next / length * max;
 	time_from = CLAMP(time_from, 0, max - 1);