[PostGIS] #5699: ERROR: XX000: SQL/MM Spatial exception - geometry crosses an edge

[PostGIS]

#5699: ERROR:  XX000: SQL/MM Spatial exception - geometry crosses an edge
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  Reporter:  Lars Aksel Opsahl  |      Owner:  strk
      Type:  defect             |     Status:  assigned
  Priority:  medium             |  Milestone:  PostGIS 3.4.3
 Component:  topology           |    Version:  3.4.x
Resolution:                     |   Keywords:  robustness
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Comment (by strk):

 Raising an exception instead of silently creating an invalid topology is
 done in this PR: https://git.osgeo.org/gitea/postgis/postgis/pulls/195

 With the code in that PR we now get, upon adding the final line:
 {{{
 ERROR:  Spatial exception - geometry boundary touches interior of edge 1
 }}}

 This is still puzzling because the boundary of the geometry is supposed to
 be the same as the new node being created upon splitting edge 2, so if
 that boundary touches interior of edge 1 then also the added point should,
 but was found to be at a squared distance of `1.64235648202829e-31` units.

 I suspect GEOS is internally reducing the precision of the geometries upon
 catching a topology error due to the same robustness troubles we are
 having.
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5699#comment:7>
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