Warn about invalid text selections
Warn about invalid text selections

FIX: Creating a `TextSelection` with endpoints that don't point at inline positions
now emits a warning. (It is technically an error, but crashing on it might be too
disruptive for some existing setups.)

See https://discuss.prosemirror.net/t/selection-changes-when-inline-decoration-is-applied/1027/11
See https://discuss.prosemirror.net/t/strange-behavior-with-textselection/4400

ProseMirror/prosemirror-state