message property

@override String get message

What is wrong and how to fix it, in one paragraph.

Implementation

@override
String get message =>
    'references the variable "$name", which the Stack does not declare. '
    "Declare it with `variable<T>('$name')`, or with "
    "`externalVariable<T>('$name')` when a hand-written file beside "
    'main.tf.json declares it.';