Merge #15685: doc: rpc-mining: Clarify error messages

fa292ad doc: rpc-mining: Clarify error messages (MarcoFalke)

Pull request description:

  Fixes #13274

ACKs for commit fa292a:
  fanquake:
    tACK fa292ad

Tree-SHA512: 58946a52ce49b97c35cbf5eaa9175447a231690cb2bac0d39e5db524bdf2cbad274a905038aca270c080d5660f58176d43c01a22a8417c0f5b8276816939c1d6

Author: MarcoFalke

src/rpc/mining.cpp

@@ -444,10 +444,10 @@ static UniValue getblocktemplate(const JSONRPCRequest& request)
         throw JSONRPCError(RPC_CLIENT_P2P_DISABLED, "Error: Peer-to-peer functionality missing or disabled");
 
     if (g_connman->GetNodeCount(CConnman::CONNECTIONS_ALL) == 0)
-        throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, "Bitcoin is not connected!");
+        throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, PACKAGE_NAME " is not connected!");
 
     if (IsInitialBlockDownload())
-        throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, "Bitcoin is downloading blocks...");
+        throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, PACKAGE_NAME " is in initial sync and waiting for blocks...");
 
     static unsigned int nTransactionsUpdatedLast;