Attached nav-file raises error:
core.rinex.basic.RinexError: can't read navigation message: 0.179984000000D+06 0.000000000000D+00 0.499063314674-269 0.664593648549-315 (nav/brdc2970.12n.Z)
I suppose it is due to big negative degree values (0.499063314674-269, 0.664593648549-315)
ftp://cddis.gsfc.nasa.gov/gnss/data/daily/2012/297/12n/brdc2970.12n.Z