NPE in getAccountInfo() if result is nil

[riptl]

If a non-compliant RPC server returns result: null for getAccountInfo(), the client will panic with null pointer deref (line 127 on out.Value because out is nil).

https://github.com/gagliardetto/solana-go/blob/dd0af958252d8cdd28db04a39fc67103223946cc/rpc/getAccountInfo.go#L123-L127

Ideally the RPC client would never panic under any circumstances

[gagliardetto]

How about

if out == nil || out.Value == nil { 

but in that case, can we be sure that out == nil means not found ?

[riptl]

imo, out == nil violates the spec, so it's best to error here instead of assuming a valid result. Maybe we could wrap CallForInto to return an error if out == nil after unmarshaling.

[gagliardetto]

In some cases, result == nil follows the spec (e.g. getBlock: https://github.com/solana-labs/solana/blob/master/docs/src/developing/clients/jsonrpc-api.md#getblock )

[gagliardetto]

if out == nil {
   return nil, errors.New("expected a value, got null response")
}

[gagliardetto]

https://github.com/gagliardetto/solana-go/commit/e6a58061889f44feecf7e5e6305cc851d06fb3a5