In both files some variable were potentially not initialized and
nevertheless used for some computation.
After checking with N.C. for xLagrangeMapping.cc the case were
knots.size() is null is impossible => assert. Then a simple init with
first point remove the warning and set without ambiguity x1,y1,z1.
For xMapping.cc the switch was not defaulted and thus DetJac may remain
unset. Setting it to 1 and put a default case in switch solve the prb.