Changed check for RPC JSON response success [v1.0]

[poriyaalarsamvelraja]

Fixes #930

According to RPC JSON format 2.0

This member MUST NOT exist if there was an error invoking the method.

The condition if(payload.result) would fail if the result is null which is true for many success cases.

for example for wallet_switchEthereumChain

[poriyaalarsamvelraja]

Thanks @pedrouid

[pedrouid]

@poriyaalarsamvelraja I have published v1.7.8 with these changes

[poriyaalarsamvelraja]

Thanks Mate