connect equations ignore missing components?

[Bill Janssen]

I'm looking at this model from the MSL, 
Modelica.Mechanics.Rotational.Interfaces:

    partial model PartialOneFlangeAndSupport
      parameter Boolean useSupport=false
        "= true, if support flange enabled, otherwise implicitly grounded";
      Flange_b flange "Flange of shaft";
      Support support if useSupport;
    protected
      Support internalSupport;
      Components.Fixed fixed if not useSupport;
    equation
      connect(support, internalSupport);
      connect(internalSupport, fixed.flange);

This seems broken to me.  Shouldn't there be if-equations around the
connect equations?  Either "support" or "fixed" is going to be missing.
Won't that raise errors?  How is OpenModelica OK with this?

Bill