SI-8263 Avoid SOE in logicallyEnclosingMember

Not sure when the regression hit, but we're seeing this in the
SBT build. It's probably a mistake to be calling this method
on somthing that isn't owned by a method, but let's not SOE
in that case.

This is analagous with the way the `NoSymbol#owner` doesnt throw
and exception anymore.

Review by @gkossakowski