fix: don't throw error in rulers if map file is corrupted

modules/ui/measurers.js

@@ -16,21 +16,20 @@ class Rulers {
   fromString(string) {
     this.data = [];
 
+    const typeMap = {
+      Ruler: Ruler,
+      Opisometer: Opisometer,
+      RouteOpisometer: RouteOpisometer,
+      Planimeter: Planimeter
+    };
+
     const rulers = string.split("; ");
     for (const rulerString of rulers) {
       const [type, pointsString] = rulerString.split(": ");
+      if (!type || !pointsString) continue;
+
       const points = pointsString.split(" ").map(el => el.split(",").map(n => +n));
-      const Type =
-        type === "Ruler"
-          ? Ruler
-          : type === "Opisometer"
-          ? Opisometer
-          : type === "RouteOpisometer"
-          ? RouteOpisometer
-          : type === "Planimeter"
-          ? Planimeter
-          : null;
-      this.create(Type, points);
+      this.create(typeMap[type], points);
     }
   }