Deleting from empty section, then calling block command gets undefined rng.

[lkmill]

This does not seem to break anything, including the undo/redo. However, the selection gets unset (user needs to click in spytext field again to continue working).

Uncaught TypeError: Cannot read property 'commonAncestorContainer' of null
module.exports.updateContained @ selectron.js:558
module.exports.update @ selectron.js:499
module.exports.restore @ selectron.js:453
block @ commands.js:122
module.exports.require.extend.command @ field.js:132
module.exports.require.extend.listCommand @ toolbar.js:90
m.event.dispatch @ jquery.js:4670
r.handle @ jquery.js:4338
selectron.js:282