whatwg/webidl#1211 defines a pattern for interfaces deriving from DOMException. However, it writes the IDL with an optional argument followed by a required argument, which widlparser can't currently handle: plinss/widlparser#79
Once widlparser is updated we should fix our IDL. In the meantime, I have a workaround which should behave exactly the same way.
whatwg/webidl#1211 defines a pattern for interfaces deriving from
DOMException. However, it writes the IDL with an optional argument followed by a required argument, which widlparser can't currently handle: plinss/widlparser#79Once widlparser is updated we should fix our IDL. In the meantime, I have a workaround which should behave exactly the same way.