Snapping on segment does not create topological points to all layers

[vaahtokarkki]

What is the bug or the crash?

When snapping is enabled for all layers, digitizing a new feature with vertex tool does not create topological points for all layers, if the snapped segment is shared by multiple layers:

Steps to reproduce the issue

• Open snapping.zip project (open from - geopackage)
• Enable editing for all three layers
• Make sure topological editing is enabled
• Make sure snapping on segment and all layers is enabled
• Digitize new feature for line layer
  • Snap to the shared boundary of both polygons
• Topological point is created only for feature in polygon 1 layer

Versions

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QGIS version	3.36.0-Maidenhead	QGIS code revision	09951dc
Qt version	5.15.3
Python version	3.9.18
GDAL/OGR version	3.8.4
PROJ version	9.3.1
EPSG Registry database version	v10.098 (2023-11-24)
GEOS version	3.12.1-CAPI-1.18.1
SQLite version	3.41.1
PDAL version	2.6.0
PostgreSQL client version	16.1
SpatiaLite version	5.1.0
QWT version	6.1.6
QScintilla2 version	2.13.4
OS version	Windows 10 Version 2009
Active Python plugins
db_manager	0.1.20
grassprovider	2.12.99
MetaSearch	0.3.6
processing	2.12.99

QGIS version 3.36.0-Maidenhead QGIS code revision [09951dc](https://github.com/qgis/QGIS/commit/09951dc0) Qt version 5.15.3 Python version 3.9.18 GDAL/OGR version 3.8.4 PROJ version 9.3.1 EPSG Registry database version v10.098 (2023-11-24) GEOS version 3.12.1-CAPI-1.18.1 SQLite version 3.41.1 PDAL version 2.6.0 PostgreSQL client version 16.1 SpatiaLite version 5.1.0 QWT version 6.1.6 QScintilla2 version 2.13.4 OS version Windows 10 Version 2009

Active Python plugins
db_manager
0.1.20
grassprovider
2.12.99
MetaSearch
0.3.6
processing
2.12.99

<style type="text/css"> p, li { white-space: pre-wrap; } </style>

QGIS version	3.34.1-Prizren	QGIS code revision	1339274
Qt version	5.15.3
Python version	3.9.5
GDAL/OGR version	3.8.0
PROJ version	9.3.0
EPSG Registry database version	v10.094 (2023-08-08)
GEOS version	3.12.1-CAPI-1.18.1
SQLite version	3.41.1
PDAL version	2.6.0
PostgreSQL client version	15.2
SpatiaLite version	5.1.0
QWT version	6.1.6
QScintilla2 version	2.13.4
OS version	Windows 10 Version 2009
Active Python plugins
db_manager	0.1.20
grassprovider	2.12.99
MetaSearch	0.3.6
processing	2.12.99

QGIS version 3.34.1-Prizren QGIS code revision [1339274](https://github.com/qgis/QGIS/commit/133927424d) Qt version 5.15.3 Python version 3.9.5 GDAL/OGR version 3.8.0 PROJ version 9.3.0 EPSG Registry database version v10.094 (2023-08-08) GEOS version 3.12.1-CAPI-1.18.1 SQLite version 3.41.1 PDAL version 2.6.0 PostgreSQL client version 15.2 SpatiaLite version 5.1.0 QWT version 6.1.6 QScintilla2 version 2.13.4 OS version Windows 10 Version 2009

Active Python plugins
db_manager
0.1.20
grassprovider
2.12.99
MetaSearch
0.3.6
processing
2.12.99

Supported QGIS version

• I'm running a supported QGIS version according to the roadmap.

New profile

• I tried with a new QGIS profile

Additional context

No response

[JuhoErvasti]

I noticed another related issue; if you're trying to edit only one of the layers and it has overlapping segments with the other layer the topological point is added to neither one of them since it is only added to the snapped layer (see #37824).

The order in which layers are snapped to seems to be dependent on the order in the layer panel.