A complex field whose `fldChar` `separate` or `end` arrives while the
field is still in the `FldCharOpen` state (no `w:instrText` was read,
e.g. for a dead cross-reference, or when the instruction sits inside a
tracked change) hit the catch-all case and left the field stack
unchanged. The leaked entry combined with the next ordinary field to
leave a `FldCharContent` on the stack for the rest of the document,
which swallowed the content of every following list item.
Treat such fields as unknown fields, and pop a finished field even
when its parent field is not yet in its content.
Closes#11943.
enieuwy
879e2b8646