Fix bug that caused the lowres to be saved to disk constantly

Author: TBlueF

BlueMapCommon/src/main/java/de/bluecolored/bluemap/common/RenderManager.java

@@ -127,8 +127,10 @@ private void renderThread() {
 					RenderTask task = renderTasks.peek();
 					if (task != null) {
 						ticket = task.poll();
-						if (task.isFinished()) renderTasks.poll();
-						task.getMapType().getTileRenderer().save();
+						if (task.isFinished()) {
+							renderTasks.poll();
+							task.getMapType().getTileRenderer().save();
+						}
 					}
 				}
 			}