Disallow type declarations for local variables in scopes where it's impossible to call them

[nobodywasishere]

This gives an error:

def hello(begin)
end

While this does not:

def hello(begin : String)
end

It should not be possible to declare a local variable within a scope that it's impossible to call within.

[Sija]

Another example:

raise : String = "foo"
begin : String = "foo"
end : String = "foo"
do : String = "foo"

# and possibly many other keywords (if not all)...

[nobodywasishere]

type works, but that may be due to them only being used inside lib bodies.