Fixed #8119

core/assets/bundles/bundle.properties

@@ -292,6 +292,7 @@ server.invalidport = Invalid port number!
 server.error = [scarlet]Error hosting server.
 save.new = New Save
 save.overwrite = Are you sure you want to overwrite\nthis save slot?
+save.nocampaign = Individual save files from the campaign cannot be imported.
 overwrite = Overwrite
 save.none = No saves found!
 savefail = Failed to save game!

core/src/mindustry/maps/planet/SerpuloPlanetGenerator.java

@@ -656,6 +656,11 @@ public class SerpuloPlanetGenerator extends PlanetGenerator{
     public void postGenerate(Tiles tiles){
         if(sector.hasEnemyBase()){
             basegen.postGenerate();
+
+            //spawn air enemies
+            if(spawner.countGroundSpawns() == 0){
+                state.rules.spawns = Waves.generate(sector.threat, new Rand(sector.id), state.rules.attackMode, true, false);
+            }
         }
     }
 }

core/src/mindustry/net/ArcNetProvider.java

@@ -264,7 +264,7 @@ public class ArcNetProvider implements NetProvider{
                     callback.get(host);
                     foundAddresses.add(packet.getAddress());
                 }catch(Exception e){
-                    //don't crash when there's an error pinging a a server or parsing data
+                    //don't crash when there's an error pinging a server or parsing data
                     e.printStackTrace();
                 }
             }

core/src/mindustry/ui/dialogs/LoadDialog.java

@@ -192,6 +192,11 @@ public class LoadDialog extends BaseDialog{
         buttons.button("@save.import", Icon.add, () -> {
             platform.showFileChooser(true, saveExtension, file -> {
                 if(SaveIO.isSaveValid(file)){
+                    var meta = SaveIO.getMeta(file);
+
+                    if(meta.rules.sector != null){
+                        ui.showErrorMessage("@save.nocampaign");
+                    }else{
                         try{
                             control.saves.importSave(file);
                             rebuild();
@@ -199,6 +204,7 @@ public class LoadDialog extends BaseDialog{
                             e.printStackTrace();
                             ui.showException("@save.import.fail", e);
                         }
+                    }
                 }else{
                     ui.showErrorMessage("@save.import.invalid");
                 }