Error: Fatal when using ICurve::QueryTangent for a network edge
** Fixed at ArcGIS 8.2 **
When acquiring the polyline geometry of a geometric network edge, if the result returns an empty polyline, using the ICurve::QueryTangent method on the empty polyline geometry causes ArcMap to crash.
This is a known issue.
Solution or Workaround
Use a conditional statement that tests to make sure the geometry is not empty before using ::QueryTangent.