OptionalcauseAdditional tokens which have been re-synced in error recovery due to the original error. This information can be used the calculate the whole text area which has been skipped due to an error. For example for displaying with a red underline in a text editor.
OptionalstackThe token which caused the parser error.
An exception of this type will be saved in BaseParser.errors when BaseParser.AT_LEAST_ONE_SEP or BaseParser.AT_LEAST_ONE_SEP was called but failed to match even a single iteration.