wrong v-for Map typings?

[johnsoncodehk]

Discussed in #542

^{Originally posted by j4k0xb October 1, 2021}
when iterating through a map, its typically done like this:

<div v-for="[key, value] in map"

My attempt of also accessing the index:

<div v-for="([key, value], a, b) in map"

a is typed as keyof Map (all the 'clear', 'delete', etc. methods)
and b is typed as a number

but actually a is the index and b is always undefined (when printing it)
bug in volar?