LazyVal => Bug fix : missing possibly undefined type

helpers/LazyVal.ts

 class LazyVal<T> {
-    private val: T = null;
+    private val: T | undefined = undefined;
 
     constructor(private valLoader: () => Promise<T> | T) {}
 
     get value(): Promise<T> {
         return new Promise<T>(async (resolve) => {
-            if ( this.val === null ) {
+            if ( this.val === undefined ) {
                 this.val = await this.valLoader();
             }
 
@@ -14,11 +14,11 @@ class LazyVal<T> {
     }
 
     reset() {
-        this.val = null;
+        this.val = undefined;
     }
 
     get isValueLoaded(): boolean {
-        return this.val !== null;
+        return this.val !== undefined;
     }
 }