< util_blitter_generate_mipmap: Assertion `!util_format_has_stencil(desc)' failed.
I think debian Mesa packages should disable these assertions, that was disabled before in 18.2.8 and earlier...
Maybe it is leftover because of Meson build system now, that have assertions enabled by default, so flag to disable assertions is -Db_ndebug=true
"
-Db_ndebugThis option controls assertions in meson projects. When set to false
(the default) assertions are enabled, when set to true they are disabled. This
is unrelated to the buildtype; setting the latter to
release will not turn off assertions.
"
https://www.mesa3d.org/meson.html