InferCoerce

type

type InferCoerce = T extends { coerce?: (v: any) => infer R }
  ? [R] extends [never]
    ? TFallback
    : R extends undefined
    ? TFallback
    : R
  : TFallback;

Infer the coerced type. If coerce function exists, use its return type.
Otherwise fall back to the provided fallback type.

Uses optional property matching coerce?: to handle configs where coerce
is defined as optional (like ObjectOptionConfig).

Special handling:

[R] extends [never]: When coerce is missing/undefined, R infers as never
R extends undefined: When coerce explicitly returns undefined