ST_ExteriorRing ERROR when NULL documented

[lijat]

The following query returns an error and not null as the documentation indicates

select ST_ExteriorRing(ST_Point(1,2));

ERROR: ExteriorRing: geom is not a polygon

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SELECT PostGIS_full_version();

POSTGIS="2.1.4 r12966" GEOS="3.4.2-CAPI-1.8.2 r3921" PROJ="Rel. 4.8.0, 6 March 2012" GDAL="GDAL 1.10.1, released 2013/08/26" LIBXML="2.9.1" LIBJSON="UNKNOWN" RASTER

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the documentation here ​http://postgis.net/docs/ST_ExteriorRing.html states that

"Return NULL if the geometry is not a polygon."

[pramsey]

Hm, ST_InteriorRingN displays the same behavior.

On the other hand, ST_NumInteriorRings() returns NULL for non-geometry types.

So we've got a certifiable mishmash.

[pramsey]

In 15785:

Harmonize behavior of ExteriorRing / InteriorRingN
and NumInteriorRings on returning NULL on bad input
instead of errors, matching the doco
(Closes #3261)