Facing issue while using API

Question

Step 1. I create new project using this command "wac create --company "{!Company Name}" --tool "{!Tool Name}""

Step 2. I resolved some error

Step 3. After that when i did "ng serve", My UI screen is visible on window admin center while running the server .

Step 4. when i try to hit any API -> I am getting core error

Pls help on this.