Gird: add column "back" (after removal) may lead to an exception.

[denis-anisimov]

Use GridColspans UI from here: https://github.com/vaadin/framework/tree/589-grid-tests-migration. Click "Show/Hide first name" button. The result: column disappears. Click one more time to the same button. Expected: Column should be added back (there is an open question what should happen with merged cells). The result (might be related or not to the joined columns functionality):

java.lang.IllegalArgumentException: No cell found for column id 5 at com.vaadin.ui.components.grid.StaticSection$StaticRow.internalGetCell(StaticSection.java:219) at com.vaadin.ui.components.grid.StaticSection$StaticRow.getCell(StaticSection.java:202) at com.vaadin.ui.components.grid.Footer$Row.getCell(Footer.java:1) at com.vaadin.ui.Grid.lambda$4(Grid.java:2001) at java.util.ArrayList.forEach(ArrayList.java:1249) at java.util.Collections$UnmodifiableCollection.forEach(Collections.java:1080) at com.vaadin.ui.Grid.iterator(Grid.java:2000) at com.vaadin.server.AbstractClientConnector.getAllChildrenIterable(AbstractClientConnector.java:536) at com.vaadin.ui.ConnectorTracker.isHierarchyComplete(ConnectorTracker.java:451) at com.vaadin.ui.ConnectorTracker.cleanConnectorMap(ConnectorTracker.java:286) at com.vaadin.server.communication.UidlWriter.write(UidlWriter.java:334) at com.vaadin.server.communication.UidlRequestHandler.writeUidl(UidlRequestHandler.java:124) at com.vaadin.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:92) at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:41) at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1450) at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:380) at com.vaadin.launcher.ApplicationRunnerServlet.service(ApplicationRunnerServlet.java:160) at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)

[pleku]

Related to #493 ? Which is the same as vaadin/framework#8057

[denis-anisimov]

I would say not at all.

The difference is:

• It's possible to remove a column (in this case).
• It's not possible to add it back.
• There is no client side exception (at least I don't see it). There is a server side exception.