Fragment with negative length

a negative fragment length was observed during fragmentation/reverse transcription:

[LIBRARY] Reverse Transcription
[LIBRARY] Configuration
Mode: RH
PWM: default
RT MIN: 500
RT MAX: 5500

Processing Fragments * FAILED
[ERROR] Error while fragmenting : fromIndex(173) > toIndex(171)
java.lang.IllegalArgumentException: fromIndex(173) > toIndex(171)
at java.util.Arrays.rangeCheck(Arrays.java:794)
at java.util.Arrays.binarySearch(Arrays.java:1271)
at barna.flux.simulator.fragmentation.FragmentReverseTranscription.process(FragmentReverseTranscription.java:360)
at barna.flux.simulator.fragmentation.Fragmenter.process(Fragmenter.java:596)
at barna.flux.simulator.fragmentation.Fragmenter.call(Fragmenter.java:222)
at barna.flux.simulator.SimulationPipeline.call(SimulationPipeline.java:440)
at barna.flux.simulator.SimulationPipeline.call(SimulationPipeline.java:54)
at barna.commons.launcher.Flux.main(Flux.java:198