Fix lazy initialization of instances in RegisterInstance

Updated the lazy initialization logic to ensure the instance is created only once by moving the instance variable outside of the proxy handlers. This addresses potential redundant instance creation and improves efficiency and consistency in DI container operations.

src/decorators/RegisterInstance.ts

@@ -31,32 +31,33 @@ export function RegisterInstance<
     return function (constructor: TargetType, ...args: unknown[]): void {
         // Get the instance of the DI container
         const diContainer = TSinjex.getInstance();
+        let instance: InstanceType<TargetType>;
 
         // Create a proxy to instantiate the class when needed (Lazy Initialization)
         let lazyProxy: unknown = new Proxy(
             {},
             {
                 get(target, prop, receiver) {
-                    let instance: InstanceType<TargetType>;
-
+                    if (instance == null) {
                         if (init) {
                             instance = init(constructor);
                         } else {
                             instance = new constructor(...args);
                         }
+                    }
                     lazyProxy = instance;
 
                     // Return the requested property of the instance
                     return instance[prop as keyof InstanceType<TargetType>];
                 },
                 set(target, prop, value, receiver) {
-                    let instance: InstanceType<TargetType>;
-
+                    if (instance == null) {
                         if (init) {
                             instance = init(constructor);
                         } else {
                             instance = new constructor(...args);
                         }
+                    }
                     lazyProxy = instance;
 
                     // Set the requested property of the instance