Hi.

If you take a look at the library "doc" https://github.com/ruimarinho/bitcoin-core#getblockchaininformationcallback the function is
getBlockchainInformation
If I use getBlockchainInfo I get "TypeError: client.getblockchaininfo is not a function"
Using "bitcoin-cli getblockchaininfo" external command, works perfectly.

I am surprised not to find a single complete example using the client.

Using postman with url localhost:8332/rest/tx/b4dd08f32be15d96b7166fd77afd18aece7480f72af6c9c7f9c5cbeb01e686fe.json and body parameters: username=xxx & password=yyy I get the same: "404 Not Found"