Issue #1: Create ErrorHandler

src/ErrorHandler.ts

+import {UserInterface} from "./User"
+
+export class ErrorHandler {
+
+    public static userHandler (input: any) {
+
+        if (typeof input.name !== "string")
+            throw new Error("Invalid user name");
+        
+        if (typeof input.email !== "string")
+            throw new Error("Invalid user email");
+
+        const newUser: UserInterface = {
+            userName = input.name,
+            userEmail = input.email
+        }
+
+        return newUser;
+    }
+}
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