ArrayIndexOutOfBoundException in Spreadsheet.handleRowSizes when using a ComponentFactory

Vaadin version 8.4.5, Spreadsheet 2.1.0.alpha1

Minimal example to reproduce - just click the button.

package foo.bar;

import javax.servlet.annotation.WebServlet;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Sheet;

import com.vaadin.addon.spreadsheet.Spreadsheet;
import com.vaadin.addon.spreadsheet.SpreadsheetComponentFactory;
import com.vaadin.annotations.Theme;

import com.vaadin.annotations.VaadinServletConfiguration;
import com.vaadin.server.VaadinRequest;
import com.vaadin.server.VaadinServlet;
import com.vaadin.ui.Button;
import com.vaadin.ui.ComboBox;
import com.vaadin.ui.Component;
import com.vaadin.ui.UI;
import com.vaadin.ui.VerticalLayout;

@Theme("mytheme")
public class MyUI extends UI {

    @Override
    protected void init(VaadinRequest vaadinRequest) {
        final VerticalLayout layout = new VerticalLayout();
		Spreadsheet sheet = new Spreadsheet(6, 6);
		sheet.setSpreadsheetComponentFactory(getFactory());
        
		Button b = new Button("New entry");
		b.addClickListener(e -> addRow(sheet));

		layout.addComponent(b);
		layout.addComponent(sheet);
		setContent(layout);

    }

    private SpreadsheetComponentFactory getFactory() {
    	SpreadsheetComponentFactory f = new SpreadsheetComponentFactory() {
			
			@Override
			public void onCustomEditorDisplayed(Cell cell, int rowIndex, int columnIndex, Spreadsheet spreadsheet, Sheet sheet,
					Component customEditor) {
			}
			
			@Override
			public Component getCustomEditorForCell(Cell cell, int rowIndex, int columnIndex, Spreadsheet spreadsheet,
					Sheet sheet) {
				return null;
			}
			
			@Override
			public Component getCustomComponentForCell(Cell cell, int rowIndex, int columnIndex, Spreadsheet spreadsheet,
					Sheet sheet) {
				if((columnIndex==1))
					return new ComboBox();
				else
					return null;
			}
		};
		return f;
	}

	private void addRow(Spreadsheet sheet) {
		int rows = sheet.getRows();
		sheet.shiftRows(1, rows, 1);
		sheet.setMaxRows(rows + 1);
	}

	@WebServlet(urlPatterns = "/*", name = "MyUIServlet", asyncSupported = true)
    @VaadinServletConfiguration(ui = MyUI.class, productionMode = false)
    public static class MyUIServlet extends VaadinServlet {
    }
}

Possibly similar cause as #459 but at a different place in the code.

Start with the minimal example in the issue and reproduce the exception by clicking “New entry” with a SpreadsheetComponentFactory configured. Inspect Spreadsheet.handleRowSizes and compare the related behavior in issue #459. Done means inserting a row no longer raises ArrayIndexOutOfBoundException when a component factory supplies a custom component.