A DESCRIPTION OF THE PROBLEM :
This is very similar to RT-32621, a bug in TreeTableCell, fixed some time ago by introducing indexExceedsItemCount in updateItem(int).
I believe that ListCell and TreeCell should be fixed at the same time. Sadly, they were not.

Please compare
https://hg.openjdk.java.net/openjfx/9/rt/file/tip/modules/javafx.controls/src/main/java/javafx/scene/control/TreeTableCell.java#l626
with
https://hg.openjdk.java.net/openjfx/9/rt/file/tip/modules/javafx.controls/src/main/java/javafx/scene/control/ListCell.java#l486
and
https://hg.openjdk.java.net/openjfx/9/rt/file/tip/modules/javafx.controls/src/main/java/javafx/scene/control/TreeCell.java#l531.

Related bug (mentioned earlier):
https://bugs.openjdk.java.net/browse/JDK-8115233
Possibly related bug (null items + list view):
https://bugs.openjdk.java.net/browse/JDK-8181907


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Add 2 items to the list, then remove 1. The 2nd item will be still editable.

Setting custom cell factory (TextFieldListCell) is not essential to this bug, but it makes things easier to see. Please check ListView strange behavior without setting it too.



---------- BEGIN SOURCE ----------
package sandbox;

import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ListView;
import javafx.scene.control.cell.TextFieldListCell;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class Main extends Application {
public static void main(String[] args) {
launch(args);
}

@Override
public void start(Stage primaryStage) throws Exception {
ObservableList<String> items = FXCollections.observableArrayList();

ListView<String> list = new ListView<>(items);

// it's easier to see this bug when custom cell factory is used
list.setCellFactory(TextFieldListCell.forListView());
list.setEditable(true);

Button minus = new Button("-");
Button plus = new Button("+");
minus.disableProperty().bind(Bindings.isEmpty(items));
minus.setOnAction(e -> items.remove(items.size() - 1));
plus.setOnAction(e -> items.add(null));

VBox root = new VBox(new HBox(minus, plus), list);

Scene scene = new Scene(root, 400, 300);
primaryStage.setScene(scene);
primaryStage.show();
}
}

---------- END SOURCE ----------