Bugs in x402-fetch

[juchiast]

We tried to use x402-fetch to send POST request and discovered some bugs:

1. "request body is already used" error when sending the request a second time

When you call

x402/typescript/packages/x402-fetch/src/index.ts

Line 63 in 0761c76

const response = await fetch(input, init);

the fetch function consume the body, therefore when you call the request again, the body is already gone, leading to the error.

2. Any custom headers will be discarded when you pass an already built Request to fetch

x402/typescript/packages/x402-fetch/src/index.ts

Lines 106 to 110 in 0761c76

	headers: {
	...(init?.headers || {}),
	"X-PAYMENT": paymentHeader,
	"Access-Control-Expose-Headers": "X-PAYMENT-RESPONSE",
	},

These headers will replace the headers of input, not extend it, so if someone use:

fetch(new Request("http://example.com", {
// custom headers
}));

The headers will be gone in the second request.

We've published a fixed version of the library at https://jsr.io/@space-operator/x402-fetch and will open a PR here.