Sometimes when the parser is performing error recovery it skips tokens
until it finds the next `,` or `;`, to try to get back on track. This
is handled by the `Parser.findNextCommaOrSemicolon` method.
When this method encounters a `BeginToken` (i.e., `(`, `[`, `{`, or
`<`), it needs to skip to the matching end token (using the `endToken`
getter), so that it doesn't try to resume parsing inside some nested
structure.
However, sometimes there is no matching end token (either because the
user has failed to properly matched `()`, `[]`, or `{}`, or because
the `BeginToken` is `<`, which doesn't always have a matching `>`). To
avoid a crash when this happens, `Parser.findNextCommaOrSemicolon`
needs to treat an unmatched `BeginToken` like an ordinary token, and
just advance to the next token.
Fixes https://github.com/dart-lang/sdk/issues/54236.
Bug: https://github.com/dart-lang/sdk/issues/54236
Change-Id: Id208c7a46c9c00b69f7f460a638d59486ebaffea
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/339980
Reviewed-by: Jens Johansen <jensj@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
Paul Berry
08405de9c6