Improve error message for field accesses in secondary constructors

[biboudis]

class Foo(x : Any) {
  val foo : Integer = 0

  def this() = {
    this(foo)
  }
}

-- [E006] Unbound Identifier Error: /Users/bibou/Projects/EPFL/dotty/compiler/../tests/run/tMain.scala:5:9 -------------
5 |    this(foo)
  |         ^^^
  |         not found: foo
    Compilation failed for: '../tests/run/tMain.scala'    

[Varunram]

@biboudis Very basic question, but how would you detect whether it is indeed inside a secondary class? For example, when I run this(foo) instead of it like
def this() = { this(foo) },
it prints the same error message right? Thanks!