지붕면 할당 시 오류 수정

src/hooks/usePolygon.js

@@ -176,6 +176,10 @@ export const usePolygon = () => {
    * @param showDirectionText
    */
   const drawDirectionArrow = (polygon, showDirectionText = true) => {
+    if (!polygon) {
+      return
+    }
+
     if (polygon.points.length < 3) {
       return
     }