soroban-rpc: returns 500 internal server error for malfomed requests

[leighmcculloch]

What version are you using?

v20.1.0

What did you do?

Sent a request with an empty body.

curl -v -X POST http://localhost:8000/soroban/rpc -H 'Content-Type: application/json'

Sent a malformed body:

curl -v -X POST http://localhost:8000/soroban/rpc -H 'Content-Type: application/json' -d '{'

What did you expect to see?

HTTP status code 400 because of the malformed body.

What did you see instead?

*   Trying [::1]:8000...
* Connected to localhost (::1) port 8000
> POST /soroban/rpc HTTP/1.1
> Host: localhost:8000
> User-Agent: curl/8.4.0
> Accept: */*
> Content-Type: application/json
> 
< HTTP/1.1 500 Internal Server Error
< Server: nginx/1.18.0 (Ubuntu)
< Date: Fri, 22 Dec 2023 00:19:54 GMT
< Content-Type: text/plain; charset=utf-8
< Content-Length: 31
< Connection: keep-alive
< Accept-Post: application/json
< Vary: Origin
< Vary: Origin
< 
[-32700] invalid request value
* Connection #0 to host localhost left intact