TS1273

'readonly' modifier cannot appear on a type parameter.

Broken Code ❌

function logValues<readonly T>(values: T[]) {
  console.log(values);
}

This error occurs because the readonly modifier is not allowed on a type parameter. Type parameters are meant to be used for generic types and should not have modifiers like readonly.

Fixed Code ✔️

You can apply readonly to the type of the array rather than the type parameter itself:

function logValues<T>(values: readonly T[]) {
  console.log(values);
}

In this fixed version, the array values is considered a read-only array, and its elements cannot be modified within the function. It is a good practice to avoid accidential modifications.