message: Fix issue in out-of-bounds reg index
diff: @@ -125,7 +125,7 @@ public:
  unsigned int regNumber(const QString& reg, bool& success) const override {
  QString regRes = reg;
  success = true;
  - if (reg[0] == 'x') {
  + if (reg[0] == 'x' && (RVRegNames.count(reg) != 0)) {
  regRes.remove('x');
  return regRes.toInt(&success, 10);
  } else if (RVRegAliases.contains(reg)) {
  