Crash when fitting a ratio without events

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A plot like this crash plotIt when fitting the ratio

Stack:

#0  0x000000379deac61e in waitpid () from /lib64/libc.so.6
#1  0x000000379de3e609 in do_system () from /lib64/libc.so.6
#2  0x00007f469a7dc85c in TUnixSystem::StackTrace() () from /gridgroup/cms/brochet/root/root-sl6/lib/libCore.so
#3  0x00007f469a7df033 in TUnixSystem::DispatchSignals(ESignals) () from /gridgroup/cms/brochet/root/root-sl6/lib/libCore.so
#4  <signal handler called>
#5  0x00007f46996945dd in ROOT::Math::WrappedMultiTF1::DoEvalPar(double const*, double const*) const () from /gridgroup/cms/brochet/root/root-sl6/lib/libHist.so
#6  0x00007f4698883e3c in ROOT::Math::OneDimParamFunctionAdapter<ROOT::Math::IParametricFunctionMultiDim const&>::DoEval(double) const () from /gridgroup/cms/brochet/root/root-sl6/lib/libMathCore.so
#7  0x00007f46988a6bef in ROOT::Math::RichardsonDerivator::Derivative1(double) () from /gridgroup/cms/brochet/root/root-sl6/lib/libMathCore.so
#8  0x00007f46988806ba in ROOT::Fit::FitResult::GetConfidenceIntervals(unsigned int, unsigned int, unsigned int, double const*, double*, double, bool) const () from /gridgroup/cms/brochet/root/root-sl6/lib/libMathCore.so
#9  0x00007f4698880d1d in ROOT::Fit::FitResult::GetConfidenceIntervals(ROOT::Fit::BinData const&, double*, double, bool) const () from /gridgroup/cms/brochet/root/root-sl6/lib/libMathCore.so
#10 0x00007f469958032a in TBackCompFitter::GetConfidenceIntervals(TObject*, double) () from /gridgroup/cms/brochet/root/root-sl6/lib/libHist.so
#11 0x00000000004c9cc5 in plotIt::TH1Plotter::plot (this=0x24e0008, c=..., plot=...) at src/TH1Plotter.cc:348
#12 0x0000000000482378 in plotIt::plot (file=..., c=..., plot=...) at include/plotters.h:14
#13 0x0000000000487be8 in plotIt::plotIt::plot (this=0x7fffcf1e75b0, plot=...) at src/plotIt.cc:458