Error thrown when merging cells with rowspan

[Comandeer]

Type of report

Bug

Provide detailed reproduction steps (if any)

1. Open https://jsfiddle.net/Comandeer/qj5367zy/
2. Open console.
3. Select column with a rowspanned cell and one other column.
4. Open context menu and choose "Cell" → "Merge cells" option.

Expected result

Cells are merged, undo step is created.

Actual result

Cells are merged, however error is thrown and no undo step is created:

ckeditor.js:154 Uncaught TypeError: Cannot read property 'type' of null
    at a (ckeditor.js:154)
    at CKEDITOR.dom.range.createBookmark2 (ckeditor.js:156)
    at Array.createBookmarks2 (ckeditor.js:515)
    at CKEDITOR.dom.selection.createBookmarks2 (ckeditor.js:468)
    at new CKEDITOR.plugins.undo.Image (ckeditor.js:1125)
    at CKEDITOR.plugins.undo.UndoManager.save (ckeditor.js:1119)
    at a.c (ckeditor.js:1114)
    at a.d (ckeditor.js:10)
    at a.<anonymous> (ckeditor.js:11)
    at a.CKEDITOR.editor.CKEDITOR.editor.fire (ckeditor.js:13)

Other details

• CKEditor version: 4.7.0+
• Installed CKEditor plugins: undo, tableselection

What's the most interesting, it's the fact that it works correctly when whole standard preset is used: https://jsfiddle.net/Comandeer/2qfhuc8z/

[corebonts]

I have this also locally, I tried to play around and I found out that if I modify the order of the plugins in your fiddle, the error goes away :D

https://jsfiddle.net/2t4hd9mj/

[corebonts]

It seems that the problem is that undo's afterCommandExec is sometimes called before the tabletools' afterCommandExec, and then the selection is not adjusted after the cell merge.

It can be fixed either in the plugin itself, or by executing the same code in a new listener, which can be used to quickfix broken applications.

    editor.on(
        "afterCommandExec",
        function (event) {
            if (event.data.name == "cellMerge") {
                // See tabletools plugin's fakeSelectCells
                var cell = event.data.commandData.cell;
                var range = editor.createRange();
                range.setStartBefore(cell);
                range.setEndAfter(cell);

                editor.getSelection().selectRanges([range]);
            }
        },
        null,
        null,
        5 // Listen with lower priority than the default (10)
    );

[Comandeer]

@corebonts, would you like to propose an official solution based on your comment? There is a whole section dedicated to contributing in our docs if you'd decide to.

[corebonts]

of course I would like to, but I don't know when I can do it.

[CKEditorBot]

Closed in #5242