Enum error: Index signature parameter type must be string or number

[vfonic]

Hi,

I have an object that has an Enum as key. The Enum values get eventualy compiled to number in JS.

I'd like to be able to specify this:
var mapping: { [mappingKey: MappingKey]: string; }
(MappingKey is Enum)

This doesn't work and throws compile errors.

Specifying mappingKey: number is not the correct behavior, as I would be able to do this in TS code then:
mapping[5] // this should throw compile error

This is a bit related to this issue:
#1415

[RyanCavanaugh]

Duplicate of #2491