Added tests for blame object source locations being srcloc structs.
Add error checking to ensure blame-source produces a srcloc? as documented.
Fix Struct-Type-Property.

Closes PR 13593.
Make scoped type vars work only for explict Alls and annotations.

Solves major issue disscussed on PR 13586.
Closes PR 13622.
Solves issue when typechecking lambdas with types like (All (a) Any).