parseFormBody(body: Uint8Array,contentType: string | null): FormBody
Parses one request body as a form — the ONE parse all three
IRequest.formData?() implementations share, and the function every
fallback path (a request without the optional accessor) calls directly.
The urlencoded arm is URLSearchParams over the decoded body, which equals
the web answer value for value, including empty values and repeated names
in wire order. The multipart arm is the promoted parseMultipart, with a
part's file-versus-text nature taken from filename !== undefined and its
text parts decoded as UTF-8.
body: Uint8Array
The raw request bytes
The parsed form
When contentType is neither form
encoding — a JSON body, a missing content-type, or a multipart type with no
boundary=. A multipart BODY that is unparseable is NOT a throw: it yields
an empty FormBody, which is the promoted parser's released behaviour and
is documented as the accessor's limit rather than hidden behind a status.