message: Default to debug variables panel if there's no high-level debug info
diff: @@ -575,6 +575,8 @@ void ShaderViewer::debugShader(const ShaderBindpointMapping *bind, const ShaderR
  m_Line2Insts.resize(m_ShaderDetails->debugInfo.files.count());
  + bool hasLineInfo = false;
  +
  for(size_t inst = 0; inst < m_Trace->lineInfo.size(); inst++)
  {
  const LineColumnInfo &line = m_Trace->lineInfo[inst];
  @@ -594,10 +596,17 @@ void ShaderViewer::debugShader(const ShaderBindpointMapping *bind, const ShaderR
  if(line.fileIndex < 0 || line.fileIndex >= m_Line2Insts.count())
  continue;
  + hasLineInfo = true;
  +
  for(uint32_t lineNum = line.lineStart; lineNum <= line.lineEnd; lineNum++)
  m_Line2Insts[line.fileIndex][lineNum].push_back(inst);
  }
  + // if we don't have line mapping info, assume we also don't have useful high-level variable
  + // info. Show the debug variables first rather than a potentially empty source variables panel.
  + if(!hasLineInfo)
  + ui->docking->raiseToolWindow(ui->debugVars);
  +
  QObject::connect(ui->stepBack, &QToolButton::clicked, this, &ShaderViewer::stepBack);
  QObject::connect(ui->stepNext, &QToolButton::clicked, this, &ShaderViewer::stepNext);
  QObject::connect(ui->runBack, &QToolButton::clicked, this, &ShaderViewer::runBack);
  