## Scenario: TypeScript Type Error

**Request:** I'm getting a TypeScript error: Type 'string' is not assignable to type 'number'.

**Debugging Process:**
1. **Reproduce:** Run `npx tsc` — error at line 42 of `userService.ts`.
2. **Isolate:** The error occurs in `calculateDiscount()`. A string is being passed where a number is expected.
3. **Hypothesis:** API response returns price as string, but function expects number.
4. **Fix:** Add `parseFloat()` conversion before passing to function.

```typescript
// Before
const discount = calculateDiscount(order.price);

// After
const discount = calculateDiscount(parseFloat(order.price));
```

5. **Verify:** TypeScript compiles cleanly. All tests pass.