Fix an NPE when a dupe node is deleted

Signed-off-by: Taylor Smock <taylor.smock@kaart.com>

src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/commands/conflation/DuplicateCommand.java

@@ -35,7 +35,7 @@ public class DuplicateCommand extends AbstractConflationCommand {
         }
 
         final List<Command> commands = new ArrayList<>();
-        if (primitiveConnections[0] instanceof Node) {
+        if (primitiveConnections[0] instanceof Node && !primitiveConnections[0].isDeleted()) {
             final Node replaceNode = (Node) primitiveConnections[0];
             final Command tCommand = replaceNode(node, replaceNode);
             if (tCommand != null) {
@@ -50,6 +50,9 @@ public class DuplicateCommand extends AbstractConflationCommand {
                 }
             }
         }
+        if (commands.isEmpty()) {
+            commands.add(new ChangePropertyCommand(node, KEY, null));
+        }
         return commands;
     }
 
@@ -92,9 +95,6 @@ public class DuplicateCommand extends AbstractConflationCommand {
             List<Command> tCommands = duplicateNode(getAffectedDataSet(), tNode);
             // We have to execute the command to avoid duplicating the command later. Undo
             // occurs later, so that the state doesn't actually change.
-            if (tCommands.isEmpty()) {
-                tCommands.add(new ChangePropertyCommand(tNode, KEY, null));
-            }
             tCommands.forEach(Command::executeCommand);
             commands.addAll(tCommands);
         }

test/unit/org/openstreetmap/josm/plugins/mapwithai/backend/commands/conflation/DuplicateCommandTest.java

@@ -10,6 +10,7 @@ import java.util.Collections;
 import org.junit.Rule;
 import org.junit.Test;
 import org.openstreetmap.josm.command.Command;
+import org.openstreetmap.josm.command.DeleteCommand;
 import org.openstreetmap.josm.data.coor.LatLon;
 import org.openstreetmap.josm.data.osm.DataSet;
 import org.openstreetmap.josm.data.osm.Node;
@@ -49,6 +50,19 @@ public class DuplicateCommandTest {
         assertTrue(dupe1.hasKey(dupe.getKey()));
         assertFalse(dupe2.hasKey(dupe.getKey()));
 
+        Command deleteDupe2 = DeleteCommand.delete(Collections.singleton(dupe2));
+        deleteDupe2.executeCommand();
+        command = dupe.getCommand(Collections.singleton(dupe1));
+        command.executeCommand();
+        assertFalse(dupe1.isDeleted());
+        assertTrue(dupe2.isDeleted());
+        assertFalse(dupe1.hasKey(dupe.getKey()));
+        command.undoCommand();
+        assertFalse(dupe1.isDeleted());
+        assertTrue(dupe1.hasKey(dupe.getKey()));
+        assertFalse(dupe2.hasKey(dupe.getKey()));
+        deleteDupe2.undoCommand();
+
         dupe1.setCoor(new LatLon(1, 1));
 
         command = dupe.getCommand(Collections.singleton(dupe1));