Spread with enum index key, invalid members don't trigger errors

TypeScript Version: 3.5.1

Search Terms:
object spread enum index missing keys

Code
Playground link has code

Expected behavior:
Missing keys & incorrect value types when I build a nested object using the spread operator with index keys, ought to throw errors for invalid types

Actual behavior:
It seems like the child object can have whatever shape I want, the types aren't being checked at all

Playground Link: This is same as above playground link

Related Issues: I'm not really sure what the root limitation that's causing this is so it's hard for me to find similar issues.