mergeDeepLeft type regression in 0.32.0

[jtojnar]

I have a helperfunction which stopped to type check when updating from 0.31.1 to 0.32.0. Simplified to:

export const fetchOptions =
    (newOpts: RequestInit) =>
    (url: string, opts: RequestInit = {}) =>
        fetch(url, mergeDeepLeft(opts, newOpts));

https://www.typescriptlang.org/play/?#code/JYWwDg9gTgLgBAbziAplA5igIilYAyKAZvAL5xFQQhwDkUAhiACYO0DcAUJygB6Sw4AYwgA7AM7wiKGEIAWAeTAxgY8XAC8nODrgAKUSgDuSmOIBccAEooAjgFcUkgJKjgMAJSaAfNt177KAAbS0koYFF0ABo4CGULaztHFzd4DURSLw1fXVyKGXkA4JjUDGxcAmIYPTizGMMTeI8PLiA

It now fails with the following error:

error TS2769: No overload matches this call.
  Overload 1 of 2, '(input: RequestInfo | URL, init?: RequestInit): Promise<Response>', gave the following error.
    Argument of type 'MergeDeepObject<RequestInit, RequestInit, BuiltIn, undefined, _OptionalKeys<RequestInit>>' is not assignable to parameter of type 'RequestInit'.
      Types of property 'body' are incompatible.
        Type 'unknown' is not assignable to type 'BodyInit'.
  Overload 2 of 2, '(input: RequestInfo | URL, init?: RequestInit): Promise<Response>', gave the following error.
    Argument of type 'MergeDeepObject<RequestInit, RequestInit, BuiltIn, undefined, _OptionalKeys<RequestInit>>' is not assignable to parameter of type 'RequestInit'.
      Types of property 'body' are incompatible.
        Type 'unknown' is not assignable to type 'BodyInit'.

38         fetch(url, mergeDeepLeft(opts, newOpts));
                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~