Initialize variables in z_getstats correctly

src/wallet/rpcwallet.cpp

@@ -3682,8 +3682,8 @@ UniValue z_getstats(const UniValue& params, bool fHelp, const CPubKey& mypk)
     if(!ReadBlockFromDisk(block, pblockindex,1))
         throw JSONRPCError(RPC_INTERNAL_ERROR, "Can't read block from disk");
 
-    int total_ztxs, total_zins, total_zouts = 0;
-    int largest_zins, largest_zouts = 0;
+    int total_ztxs = 0, total_zins = 0, total_zouts = 0;
+    int largest_zins = 0, largest_zouts = 0;
 
     // given a single block height, we calculate stats for that height
     if (params.size() == 1) {