fix node layout error and support subtree

static/icons/Error.svg

@@ -0,0 +1,10 @@
+<?xml version="1.0" ?>
+<svg height="512" viewBox="0 0 512 512" width="512" xmlns="http://www.w3.org/2000/svg">
+    <title />
+    <path
+        d="M85.57,446.25H426.43a32,32,0,0,0,28.17-47.17L284.18,82.58c-12.09-22.44-44.27-22.44-56.36,0L57.4,399.08A32,32,0,0,0,85.57,446.25Z"
+        style="fill:none;stroke:#000;stroke-linecap:round;stroke-linejoin:round;stroke-width:32px" />
+    <path d="M250.26,195.39l5.74,122,5.73-121.95a5.74,5.74,0,0,0-5.79-6h0A5.74,5.74,0,0,0,250.26,195.39Z"
+        style="fill:none;stroke:#000;stroke-linecap:round;stroke-linejoin:round;stroke-width:32px" />
+    <path d="M256,397.25a20,20,0,1,1,20-20A20,20,0,0,1,256,397.25Z" />
+</svg>