title: Type 'string' is not assignable to type '"" | "," | " " | "."'
body: <p>In my class I have a property:</p>
  <pre><code>thousandSeparator: '' | ',' | ' ' | '.';
  </code></pre>
  <p>and want to set it by:</p>
  <pre><code>const options = {
    thousandSeparator: ','
  };
  </code></pre>
  <p>when setting this I get the error</p>
  <pre><code> Types of property 'thousandSeparator' are incompatible.
   Type 'string' is not assignable to type '&quot;&quot; | &quot;,&quot; | &quot; &quot; | &quot;.&quot;'.
  </code></pre>