Improve tmpl error message (#1469)
Improve tmpl error message (#1469)

Better error message if directories are missing.

klausman/scion,klausman/scion,Oncilla/scion,Oncilla/scion,klausman/scion,Oncilla/scion,netsec-ethz/scion,klausman/scion,netsec-ethz/scion,netsec-ethz/scion,Oncilla/scion,netsec-ethz/scion,klausman/scion