Placeholder variable not recognised as object instance (PyCharm JS internal code quality linter)

Settings: EcmaScript 5.1, non-strict

So I have an object:

device = {
  ........

  emptyStr: function emptyStr(val, isSelector) {
    if (isSelector) val = $(val).val();
    return (val == undefined || val == null) ? "" : val;
  },

  copyStatus: function () {
    var self = this;
    var e    = function (val) { return self.emptyStr('#' + val, true); };  // <-- unresolved function or method emptyStr()
.........

If I replace "self" with "this", the function is easily recognised, but the code being as it is, the recognition fails, presumably because self could be modified somewhere further along the copyStatus function.

How can I instruct the linter to "recognise" "self" as actually being "this"?