TS1015

error TS1015: Parameter cannot have question mark and initializer.

Broken Code ❌

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export function getName(firstName: string, lastName?: string = 'Doe'): string {
  return `${firstName} ${lastName}`;
}

Fixed Code ✔️

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export function getName(firstName: string, lastName: string = 'Doe'): string {
  return `${firstName} ${lastName}`;
}