Prelude.head: empty list in CPF output

[jwaldmann]

tpdb-8.0/TRS/Zantema_05/z02.xml --cpf results in exception in cpf output

><semlabProc 
><model 
><finiteModel 
matchbox2014: Prelude.head: empty list

[jwaldmann]

stack dump:

><semlabProc 
><model 
><finiteModel 
*** Exception (reporting due to +RTS -xc): (THUNK_1_0), stack trace: 
  GHC.List.CAF
  --> evaluated by: CO4.Test.TermComp2014.Proof.CPF.toCpfModel.toInterpret.toArithFunction.goInts,
  called from CO4.Test.TermComp2014.Proof.CPF.toCpfModel.toInterpret.toArithFunction,
  called from CO4.Test.TermComp2014.Proof.CPF.toCpfModel.toInterpret,
  called from CO4.Test.TermComp2014.Proof.CPF.toCpfModel,
  called from CO4.Test.TermComp2014.Proof.CPF.toCpfSemLabProof.model',
  called from CO4.Test.TermComp2014.Proof.CPF.toCpfSemLabProof,
  called from CO4.Test.TermComp2014.Proof.CPF.toCpfProof.semLabProof,
  called from CO4.Test.TermComp2014.Proof.CPF.toCpfProof,
  called from CO4.Test.TermComp2014.Run.run1'.\,
  called from CO4.Test.TermComp2014.Run.run1',
  called from CO4.Test.TermComp2014.Run.run1,
  called from Main.semanticlab.\,
  called from MB.Logic.mkWork,
  called from Main.semanticlab,
  called from Main.semanticlabs.\,
  called from Main.semanticlabs,
  called from Main.handle_scc,
  called from Main.handle,
  called from Main.handle_both,
  called from MB.Logic.run,
  called from MB.Proof.CPF.dpproof,
  called from MB.Proof.CPF.proof,
  called from MB.Proof.CPF.rtoc,
  called from Main.main
matchbox2014: Prelude.head: empty list

NB: how did I get this?

cabal configure -p --ghc-options="-fprof-auto -rtsopts" --enable-library-profiling --enable-executable-profiling
cabal build -j1
./dist/build/matchbox2014/matchbox2014  ~/tpdb/tpdb-8.0/TRS/Zantema_05/z02.xml --cpf +RTS -xc

see also http://stackoverflow.com/questions/14112789/how-do-i-enable-profiling-in-a-cabal-dev-installation (but that's for cabal-dev, apparently cabal now does the same)