TL; DR: Go to every type that ends with ...Response.ts and remove readonly keywords.

A good type-system prevents problems from happening - that's why, by default, the given params to a async function in the client most be readonly. So they can't be modified while the promise is being resolved in background. Here is an example:

client.search('foo', params).then(console.log);
params.foo = 'bar'; // TYPE-ERROR: because those params may still be used inside the `search` function.

In the other hand, having readonly responses prevents the user from doing manipulations to the response object, and that's is annoying:

const response await client.search('foo', params);
delete response.hits; // TYPE-ERROR: grrrrrr
const myCustomObject = response;

Since having readonly responses add no value to the user or to us, to fix this problem, go to every type that ends with ...Response.ts and remove readonly keywords.