Gets the reference of `exports` from the given scope.

@param {escope.Scope} scope - The scope to get.
@returns {ASTNode[]} Gotten Identifier node list.
function getExportsNodes(scope) {
    const variable = scope.set.get("exports")
    if (variable == null) {
        return []
    }
    return variable.references.map(reference => reference.identifier)
}