title: What time are the installer variables initialized?
body: <p>Today we have a problem with the initialized <code>sys.installerDir</code> variable. I tried to use this variable to set the varfile location at the arguments-field in the installer screen (screenshot). It seems to be evaluated to a <code>null</code>-value and therefore the application start crashed because the file couldn't be found. The error logfile has the following entry:</p>
  
  <p><code>Could not read file [path-to-the-installer-executable]\null\plugin.config</code></p>
  
  <p>Now the question: may this be a bug or are the variables not initialized at this point?</p>
  
  <p>Thanks in advance</p>
  
  <p><img src="https://i.stack.imgur.com/WG7JC.png" alt="enter image description here"></p>