Attribute table in layout shows NULL numerical values as zeros

[aroche]

What is the bug or the crash?

See this question.

Steps to reproduce the issue

1. Add or create a vector layer with a numerical field containing some empty (NULL) values
2. Create a print layout
3. Add an attribute table object referring to the layer containing NULL values
4. The NULL values are displayed as zeros instead of empty cells

Versions

Version de QGIS	3.22.0-Białowieża	Révision du code	d902269
Version de Qt	5.15.2
Version de Python	3.9.5
Version de GDAL/OGR	3.4.0
Version de Proj	8.2.0
Version de la base de données du registre EPSG	v10.038 (2021-10-21)
Version de GEOS	3.10.0-CAPI-1.16.0
Version de SQLite	3.35.2
Version de PDAL	2.3.0
Version du client PostgreSQL	13.0
Version de SpatiaLite	5.0.1
Version de QWT	6.1.3
Version de QScintilla2	2.11.5
Version de l'OS	Windows 10 Version 1809
Extensions Python actives
changeDataSource	3.1
french_locator_filter	1.0.0
geometry_paster	0.1.1
Go2NextFeature3	2.00
profiletool	4.1.8
SpreadsheetLayers	2.0.1
StreetView	3.2
valuetool	3.0.14
ViewshedAnalysis	1.7
db_manager	0.1.20
grassprovider	2.12.99
processing	2.12.99
sagaprovider	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

[elpaso]

Can you please attach a sample project with data?

[aroche]

Here it is. Open the print layout to see the problem.
test_null_layout.zip

[pigreco]

I confirm.
i tested with both gpkg and txt

OSGeo4W v2 win 10 - QGIS 3.22.1 QGIS 3.16.14 and master

[elpaso]

What's the expected output here? An empty cell?
I don't think NULL is desired in a print layout.

[pigreco]

What's the expected output here? An empty cell?

In my opinion, the most consistent output is empty cell

[elpaso]

What's the expected output here? An empty cell?

In my opinion, the most consistent output is empty cell

I agree, that's what I have implemented in #46332