Compiler crash when autofilled array assigns instance variable in class without type reference

[SlayerShadow]

Similar to #2665 scope.

class Foo
  def some_action
    @value = Array.new( 64 ){ 64 }
  end
end

Raises compiler error (will be shown below). But other declarations works correctly:

1. value = Array.new( 64 ){ 64 } - all ok (out of class or local variable).

2. class Foo
     def some_action
       value = Array.new( 64 ){ 64 }
     end
   end

   All ok (local variable).

3. class Foo
     def bar
       @value = Array( Int32 ).new( 64 ){ 64 }
     end
   end

   All ok (type reference).

$ crystal -v
Crystal 0.24.2 [4f9ed8d03] (2018-03-08)

LLVM: 4.0.0
Default target: x86_64-unknown-linux-gnu

$ uname -a
Linux pc 4.16.0-1-amd64 #1 SMP Debian 4.16.5-1 (2018-04-29) x86_64 GNU/Linux

Error:

cast from Nil to Crystal::GenericInstanceType+ failed, at /crystal/src/compiler/crystal/types.cr:1428:20:1428
???
...
???
Error: you've found a bug in the Crystal compiler.

Backtrace is filled by "?" signs, and nothing helped to display it.

[asterite]

Duplicate of #5383