Normally Mesa (and OpenGL) records but does not notify the user of
errors. It is up to the application to call glGetError to check for
errors. Mesa supports an environment variable, MESA_DEBUG, to help
with debugging. If MESA_DEBUG is defined, a message will be printed
to stdout whenever an error occurs.
More extensive error checking is done in DEBUG builds
(--buildtype debug for Meson).
In your debugger you can set a breakpoint in _mesa_error() to trap
Mesa errors.
There is a display list printing/debugging facility. See the end of
src/dlist.c for details.