Error is thrown with zero length branches

[uyedaj]

If zero length branches are used then the following error gets thrown when executing a slide move on the zero length branch:

Error in if (m.i - 1 == 1) { : argument is of length zero

Error in if (runif(1) < exp(nll - oll + pr2 - pr1 + hr)) { : missing value where TRUE/FALSE needed