message: Don't read invalid srcOpers when evaluating texture sample operations
diff: @@ -3884,8 +3884,12 @@ void ThreadState::StepNext(ShaderDebugState *state, DebugAPIWrapper *apiWrapper,
  ddyCalc = srcOpers[4];
  }
  - int multisampleIndex = srcOpers[2].value.i.x;
  - float lodOrCompareValue = srcOpers[3].value.f.x;
  + int multisampleIndex = 0;
  + if(srcOpers.size() >= 3)
  + multisampleIndex = srcOpers[2].value.i.x;
  + float lodOrCompareValue = 0.0f;
  + if(srcOpers.size() >= 4)
  + lodOrCompareValue = srcOpers[3].value.f.x;
  if(op.operation == OPCODE_GATHER4_PO_C)
  lodOrCompareValue = srcOpers[4].value.f.x;
  