If I click "Edit" on a document when viewing the contents of a collection and then click "Save", sometimes I get an "Unexpected token ILLEGAL" error even if I didn't make any changes to the document. Based on the line number called out by the error, this seems to be caused by [ ... ] showing up where it shouldn't.
When viewing such a document in the non-edit view, there is an array field with a large number of values that is collapsed and displayed like:
fieldname: [ ... ],
When I click edit, the field is not collapsed, and is displayed like: