twiss fails for zero length solenoid

[HelmutCERN]

! twiss fails with 5.05.02, final orbit NaN
! seen for l=0 and beam with radiate
! worked with previous madx 5.04 versions

TestSeq: sequence, l = 1;
mbas2.1r1: solenoid, l=0, at = 0.5;
endsequence;
beam,radiate;
use, sequence=TestSeq;
twiss,betx=1,bety=1,sequence=TestSeq,file="TestSeq_twiss.tfs";

[tpersson]

A check is added in TWISS and TRACK to avoid this and a warning is thrown if it happens and the radiation is ignored. #858