support running joinmarket with bitcoind 29

modules/joinmarket.nix

@@ -251,6 +251,19 @@ in {
   }
 
   (mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = lib.versionOlder bitcoind.package.version "30";
+        message = ''
+          Joinmarket is not compatible with bitcoind >= 30.
+          (https://github.com/JoinMarket-Org/joinmarket-clientserver/pull/1775)
+
+          To fix this, add the following to your config:
+          services.bitcoind.package = config.nix-bitcoin.pkgs.bitcoind_29;
+        '';
+      }
+    ];
+
     services.bitcoind = {
       enable = true;
       disablewallet = false;

modules/netns-isolation.nix

@@ -341,7 +341,7 @@ in {
     services.nbxplorer.address = netns.nbxplorer.address;
     services.btcpayserver.address = netns.btcpayserver.address;
 
-    services.joinmarket = {
+    services.joinmarket = mkIf config.services.joinmarket.enable {
       payjoinAddress = netns.joinmarket.address;
       messagingAddress = netns.joinmarket.address;
       cliExec = mkCliExec "joinmarket";