When table items are set to null after items were shown first (non-null), a NPE can happen.

Stacktrace:
Exception in thread "JavaFX Application Thread" java.lang.NullPointerException: Cannot invoke "javafx.collections.ObservableList.size()" because the return value of "javafx.scene.control.TableView.getItems()" is null
at javafx.controls/javafx.scene.control.skin.TableSkinUtils.getItemCount(TableSkinUtils.java:212)
at javafx.controls/javafx.scene.control.skin.TableViewSkinBase.updateContentWidth(TableViewSkinBase.java:909)
at javafx.controls/javafx.scene.control.skin.TableViewSkinBase.checkContentWidthState(TableViewSkinBase.java:594)
at javafx.controls/javafx.scene.control.skin.TableViewSkinBase.layoutChildren(TableViewSkinBase.java:514)
at javafx.controls/javafx.scene.control.Control.layoutChildren(Control.java:612)
at javafx.graphics/javafx.scene.Parent.layout(Parent.java:1208)

Technically a regression from JDK-8137244.

Code:

import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.stage.Stage;

public class TableViewBug extends Application {

    @Override
    public void start(Stage stage) {
        TableView<String> tableView = new TableView<>();

        TableColumn<String, String> col = new TableColumn<>("123");
        col.setCellValueFactory(e -> new SimpleStringProperty(e.getValue()));
        tableView.getColumns().add(col);

        tableView.getItems().addAll("1", "2", "3");

        stage.setScene(new Scene(tableView));
        stage.show();

        tableView.setItems(null);
    }

    public static void main(String[] args) {
        launch(args);
    }

}