interpolate error spam fix

reco/detectors/trd/pid/CbmTrdSetTracksPidLike.cxx

@@ -389,6 +389,9 @@ Double_t CbmTrdSetTracksPidLike::GetProbability(Int_t k, Double_t mom, Double_t
   // and particle type k from the precalculated de/dx distributions
   //
 
+  /// check for undefined dedx (dedx = -1. is sometimes passed in)
+  if (dedx < 0.) { return -999.; }
+
   /// useless protection
   if (k < 0 || k > fgkNParts) { return -999.; }