Problem with properties with latin characters

I'm trying to use the unique filter on a property called 'InköpsNr', but I'm getting the following error:

> Lexer Error: Unexpected next character at columns 3-3 [ö] in expression [InköpsNr]

This is often an issue in Angular, but can be solved by using bracket notation instead of dot notation, i.e ['InköpsNr'] but with the unique filter it causes another error.

Is it possible to add support for latin characters in property names, or to add bracket notation support?