[TODO: update doc regarding "extensions"]
RedisExceptions are only created/raised subsequent to an error result from the redis server.
These exceptions are
_not_ intended as a general purpose exception mechanism for
implementations of this specification. Accordingly, this exception (and extensions if any)
do not (and must not) provide default no arg constructors. (Minimal information required is
an associated
Command object.)
Further, this class (and extension if any) should never expose a constructor accepting
an underlying 'cause' (as in Exception(Throwable)), since this excpetion,
to repeat, has very specific semantics: Redis has responded with an error
status to an issued command and the content of that message (e.g. "-ERR operation on wrong type"
is what is required for instantiating a RedisException.