fix(core): update

ts/lik.objectmap.ts

@@ -137,11 +137,15 @@ export class Objectmap<T> {
    */
   public getOneAndRemove(): T {
     const keys = this.fastMap.getKeys();
-    const keyToUse = keys[keys.length - 1];
+    if (keys.length === 0) {
+      return null;
+    } else {
+      const keyToUse = keys[0];
       const removedItem = this.fastMap.removeFromMap(keyToUse);
       this.eventSubject.next('remove');
       return removedItem;
     }
+  }
 
   /**
    * returns a cloned array of all the objects currently in the Objectmap
@@ -181,6 +185,5 @@ export class Objectmap<T> {
     for (const keyArg of this.fastMap.getKeys()) {
       this.fastMap.removeFromMap(keyArg);
     }
-
   }
 }