Issue Description:

When providing a single expression closure with an implicit return and takes a `Never` parameter, no warning is generated.

Examples:

func map<T>(_ block: (Never) -> T) {}
// No warning 
map { _ in 5 }
// No warning 
map { _ in
  5
}
 
// Warning
map { _ in
  return 5
}

This is very problematic when chaining results in Combine because the author is not notified that the publisher will not react accordingly.

For example, the following combine code issues no warnings and never prints a value!

somethingThatGeneratesANeverOutputPublisher()
  .map { _ in 5 }
  .sink { _ in
  } receiveValue: { value in
    print(value)
  }