[microvm] fix comparision

machines/modules/malobeo/microvm_host.nix

@@ -57,7 +57,7 @@ in
       };
     };
 
-    imports = mkIf cfg.deployHosts != [] [
+    imports = mkIf (lib.length cfg.deployHosts != 0) [
       inputs.microvm.nixosModules.host
     ];
 
@@ -73,7 +73,7 @@ in
           updateFlake = "git+https://git.dynamicdiscord.de/kalipso/infrastructure?ref=microvm";
         }; };
     in
-    mkIf cfg.deployHosts != []
+    mkIf (lib.length cfg.deployHosts != 0)
     builtins.listToAttrs (map mapperFunc cfg.deployHosts);
   };
 }