[postgis-tickets] [PostGIS] #4314: ST_AsMVTGeom: IllegalArgumentException

[PostGIS]

#4314: ST_AsMVTGeom: IllegalArgumentException
------------------------+---------------------------
 Reporter:  Algunenano  |      Owner:  Algunenano
     Type:  defect      |     Status:  assigned
 Priority:  high        |  Milestone:  PostGIS 2.4.7
Component:  postgis     |    Version:  2.4.x
 Keywords:              |
------------------------+---------------------------
 {{{
 # SELECT ST_AsMVTGeom(
     'SRID=3857;MULTIPOLYGON(((-8230700.44460474
 4970098.60762691,-8230694.76395068 4970080.40480045,-8230692.98226063
 4970074.69572152,-8230702.2389602 4970071.78449542,-8230709.99536139
 4970096.63875167,-8230700.73864062 4970099.5499925,-8230700.44460474
 4970098.60762691)))'::geometry,
     'SRID=3857;POLYGON((-8257645.03970416
 5009377.08569731,-8257645.03970416 4970241.3272153,-8218509.28122215
 4970241.3272153,-8218509.28122215 5009377.08569731,-8257645.03970416
 5009377.08569731))'::geometry,
     2048,
     8,
     true
 ) as the_geom_webmercator;
 ERROR:  lwgeom_clip_by_rect: GEOS Error: IllegalArgumentException: Invalid
 number of points in LinearRing found 3 - must be 0 or >= 4
 }}}



 I think this was introduced in #4289 so it looks like one of the functions
 that modify the geometry (`lwgeom_remove_repeated_points_in_place`,
 `lwgeom_simplify_in_place`, `lwgeom_affine` and `lwgeom_grid_in_place`)
 might be producing an invalid ring (or I'm not checking it's output
 correctly). Note that in the case where the polygon  disappeared because
 of it, MVTGeom should return NULL, not an exception.

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Ticket URL: <https://trac.osgeo.org/postgis/ticket/4314>
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