Ctrl+Z to undo on empty editor crashes the editor

Creating an empty editor with html.deserialize('<p></p>'), and then pressing Ctrl+Z crashes the editor.

Instead initialize with a raw value:

Value.fromJSON({
  document: {
    nodes: [
      {
        kind: 'block',
        type: 'paragraph',
        nodes: [
          {
            kind: 'text',
            leaves: [{ text: '' }]
          }
        ]
      }
    ]
  }
})

[ianstormtaylor]

Hey @conorcussell thanks for the super clear writeup. I’d love a PR that fixes the getSelectionIndexes case.

For the empty nodes case, Slate itself shouldn’t add a node, but I’d definitely be open to a PR that threw a more helpful error when that impossible case is run into. (Ideally in a single, or few places, wherever makes the most sense in that code path.)

Thank you!

[conorcussell]

I may just be repeating things people already know, but here are my findings from digging into this today.

When you create an empty editor the selection is unset, and an invalid selection is created because text is undefined.

https://github.com/ianstormtaylor/slate/blob/199c32a2b5f776c586e7202cfa3183e551153fe4/packages/slate/src/models/value.js#L117-L120

This also happens with copy and paste because the onPaste plugin invokes Plain.deserialize which in turn invokes Value.fromJSON

In the render method of slate-react’s content component getSelectionIndexes is called with a startKey and endKey of null, which calls getFurthestAncestor with null and gives us the error.

https://github.com/ianstormtaylor/slate/blob/199c32a2b5f776c586e7202cfa3183e551153fe4/packages/slate/src/models/node.js#L1410-L1414

Simply returning null in getSelectionIndexes when startKey and endKey are null will fix this case, and copy + pasting but it will not fix the case mentioned in https://github.com/ianstormtaylor/slate/issues/1161. If the editor won’t work without any nodes in it, should we ensure there is at least one node by default?

// if we've been passed an invalid range, we can exit early
if (!startKey && !endKey) {
  return null;
}