Avoid treating null RPC arguments different from missing arguments

This changes RPC methods to treat null arguments the same as missing arguments,
instead of throwing type errors. Specifically:

- `getbalance` method now returns the wallet balance when the `account` param
  is null instead of throwing a type error (same as when parameter is missing).
  It is still an error to supply `minconf` or `watchonly` options when the
  account is null.

- `addnode` and `setban` methods now return help text instead of type errors if
  `command` params are null (same as when params are missing).

- `sendrawtransaction`, `setaccount`, `movecmd`, `sendfrom`,
  `addmultisigaddress`, `listaccounts`, `lockunspent` methods accept null
  default values where missing values were previously allowed, and treat them
  the same.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
index e6b210a199..f19b968244 100644
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -193,7 +193,7 @@ UniValue getpeerinfo(const JSONRPCRequest& request)
 UniValue addnode(const JSONRPCRequest& request)
 {
     std::string strCommand;
-    if (request.params.size() == 2)
+    if (!request.params[1].isNull())
         strCommand = request.params[1].get_str();
     if (request.fHelp || request.params.size() != 2 ||
         (strCommand != "onetry" && strCommand != "add" && strCommand != "remove"))
@@ -490,7 +490,7 @@ UniValue getnetworkinfo(const JSONRPCRequest& request)
 UniValue setban(const JSONRPCRequest& request)
 {
     std::string strCommand;
-    if (request.params.size() >= 2)
+    if (!request.params[1].isNull())
         strCommand = request.params[1].get_str();
     if (request.fHelp || request.params.size() < 2 ||
         (strCommand != "add" && strCommand != "remove"))