(#497): Don't panic on paths with all-invalid commands

The path parser creates a PathBuilder with zero commands.

In turn, builder.to_cairo() does nothing, as expected.

But then we stroke_and_fill(), and the wrapper call to
with_discrete_layer() doesn't like not having bounds.

Fixes https://gitlab.gnome.org/GNOME/librsvg/issues/497
parent 6475ffbd
Pipeline #106940 failed with stages
in 8 minutes and 35 seconds