set duplex to 'half'

[Chuiantw1212]

According to the message, RequestInit: duplex option is required when sending a body, line 48 will always trigger the error if the duplex attribute is not set.

I tried sending a POST request from the client without any body or headers, but the error still occurred. In the case above, the keyword content-type does not exist anywhere, leaving the duplex attribute undefined.

The error stopped only when I deleted line 48, which I believe is crucial and should not be removed. Setting duplex to always 'half' seems to work.

I understand that duplex is a lab feature and may change in the future, but for now, this patch allows me to build something under development using Elysia Node.

[eliellis]

duplex: "half" seems to always be required, according to this line here, which references this issue stating as much