Inventory: warning on undefined tags, instead of error.

lib/inventory/build-inventory/default.nix

@@ -28,10 +28,10 @@ let
             );
           in
           if tagMembers == [ ] then
-            throw ''
+            lib.warn ''
               inventory.services.${serviceName}.${instanceName}: - ${roleName} tags: no machine with tag '${tag}' found.
               Available tags: ${builtins.toJSON (lib.unique availableTags)}
-            ''
+            '' []
           else
             acc ++ tagMembers
         ) [ ] members.tags or [ ]);

lib/inventory/flake-module.nix

@@ -42,7 +42,7 @@ in
       checks = {
         lib-inventory-eval = pkgs.runCommand "tests" { nativeBuildInputs = [ pkgs.nix-unit ]; } ''
           export HOME="$(realpath .)"
-
+          export NIX_ABORT_ON_WARN=1
           nix-unit --eval-store "$HOME" \
             --extra-experimental-features flakes \
             ${inputOverrides} \

lib/inventory/tests/default.nix

@@ -178,6 +178,8 @@ in
         msg = "Roles roleXYZ are not defined in the service borgbackup.";
       };
     };
+  # Needs NIX_ABORT_ON_WARN=1
+  # So the lib.warn is turned into abort
   test_inventory_tag_doesnt_exist =
     let
       configs = buildInventory {
@@ -201,8 +203,9 @@ in
     {
       expr = configs;
       expectedError = {
-        type = "ThrownError";
-        msg = "no machine with tag '\\w+' found";
+        type = "Error";
+        # TODO: Add warning matching in nix-unit
+        msg = ".*";
       };
     };
   test_inventory_disabled_service =