Regression: Segfault on wall

1. Convert 605--wall--no-geometry.ifc with 68151b9 (v0.6.0 Feb 12 – OCCT 7.3.0p3) and experience that the wall converts successfully:

2. Convert the same file with 1a57162 (v0.6.0 May 24 OCCT 7.3.0p3) and experience that there is no geomtetry output:
   Internal error, missing edge from triangulation