Make sure fetch response body is read or cancelled during flush

[athoscouto]

Not reading a fetch response can block the connection, making clients require multiple connections to keep working. In environments where the number of connections are limited, clients may experience random networking errors.

[athoscouto]

This should never happen right? We always have encoding equal to json or protobuf, no?

libsql-server should always return one of the two indeed. But we have many proxies along the way that might return something else in case of errors