and assert that symbol is not a substitution/intersection override
in the `compute` method otherwise.
Because `fakeOverrideSubstitution` should be calculated for all real
implicit types, no call to this method should actually happen.
Otherwise, it can be problematic to create a session
which would contain the full designation path:
`provider.getFirCallableContainerFile(symbol)`
returns `firFile` of a super class which might be from module `a`,
when declaration and its outer classes are from module `b`.
^KTIJ-24105
Jinseong Jeon