// Basic TypeScript file with review issues

function add(a: number, b: number): number {
    return a + b // Missing semicolon, no type safety for return
}

const result = add('1', 2); // Passing string instead of number
console.log(result)

// 1. Unused variable
let unusedVar: string;

// 2. Function with wrong return type
function getString(): number {
    return "hello" // Should return number
}

// 3. Variable declared but never used
let neverUsed = 123;

// 4. Type assertion error
let x: any = "abc";
let y: number = x as number; // Wrong assertion

// 5. Shadowed variable
let a = 5;
function shadow() {
    let a = "shadowed";
    return a;
}

// 6. Function missing return type
function noReturnType() {
    return true;
}

// 7. Incorrect interface usage
interface User {
    name: string;
    age: number;
}
const user: User = { name: "A", age: "20" }; // age should be number

// 8. Array with mixed types
const arr: number[] = [1, "2", 3];

// 9. Unreachable code
function unreachable() {
    return 1;
    console.log("This will never run");
}

// 10. Using 'any' type unnecessarily
function useAny(a: any, b: any): any {
    return a + b;
}