refactor: avoid multiple key->metadata lookups in dumpwallet RPC

This also enables working with a const ScriptPubKeyMan which was
previously not possible due to std::map::operator[] not being const.

Author: theStack

src/wallet/rpcdump.cpp

@@ -809,19 +809,22 @@ RPCHelpMan dumpwallet()
         std::string strLabel;
         CKey key;
         if (spk_man.GetKey(keyid, key)) {
+            CKeyMetadata metadata;
+            const auto it{spk_man.mapKeyMetadata.find(keyid)};
+            if (it != spk_man.mapKeyMetadata.end()) metadata = it->second;
             file << strprintf("%s %s ", EncodeSecret(key), strTime);
             if (GetWalletAddressesForKey(&spk_man, wallet, keyid, strAddr, strLabel)) {
                 file << strprintf("label=%s", strLabel);
             } else if (keyid == seed_id) {
                 file << "hdseed=1";
             } else if (mapKeyPool.count(keyid)) {
                 file << "reserve=1";
-            } else if (spk_man.mapKeyMetadata[keyid].hdKeypath == "s") {
+            } else if (metadata.hdKeypath == "s") {
                 file << "inactivehdseed=1";
             } else {
                 file << "change=1";
             }
-            file << strprintf(" # addr=%s%s\n", strAddr, (spk_man.mapKeyMetadata[keyid].has_key_origin ? " hdkeypath="+WriteHDKeypath(spk_man.mapKeyMetadata[keyid].key_origin.path) : ""));
+            file << strprintf(" # addr=%s%s\n", strAddr, (metadata.has_key_origin ? " hdkeypath="+WriteHDKeypath(metadata.key_origin.path) : ""));
         }
     }
     file << "\n";