IRR4/6 generation prefix can fail and break whole generation -> fallback or skip

[ernstjo]

If a peer is configured with filter-irr and bgpq4 cannot collect prefix list the generation stops with error:

FATA[0000] unable to get IPv4 IRR prefix list from ASxxx: exit status 1

But it shouldn't stop the whole process. Instead generate peer configwith emtpy prefix list or skip specific one but it shouldn't be stop the whole configuration generation. Thus, an empty prefixlist of any peer stops the whole config generation.

If this happens, please go in fallback with empty prefix list or skip this specific peer instead of stopping the complete process.

[missuo]

same issue