Viewer crash when asking an histogram for a "lock use" scope

[dfeneyrou]

Env: All OS
Release: 0.4
How to reproduce: simply by requesting an histogram of a lock use, for instance from a timeline "lock use" scope with contextual menu
Reproducibility: Systematic

The failed assertion is:

[PALANTEER] Assertion failed: index>=0 && index<_size 
  On function: const T& bsVec<T>::operator[](int) const [with T = bsString]
  On file    : (...)/palanteer/server/viewer/../base/bsVec.h(107)
    - int     index                = -1
    - int     _size                 = 4

  #0  bsVec.h(107) : bsVec<bsString>::operator[](int) const
  #1  vwMain.h(111) : vwMain::getFullThreadName(int) const
  #2  vwMainHistogram.cpp(92) : vwMain::_computeChunkHistogram(vwMain::Histogram&)
  #3  vwMainHistogram.cpp(388) : vwMain::drawHistograms()
  #4  vwMain.cpp(1094) : vwMain::draw()
  #5  vwPlatform.cpp(364) : vwPlatform::redraw()
  #6  vwPlatform.cpp(304) : vwPlatform::run()
  #7  vwPlatform.cpp(196) : bsBootstrap(int, char**)
  #8  bsOsLinux.cpp(826) : main