ReconstructStatesPLM causes invalid cells in RadTube problem

[chongchonghe]

Describe the bug

ReconstructStatesPLM in the RadTube problem produces invalid (ghost) cells in the RadTube problem. Using ReconstructStatesPPM clears this issue.

Note: That it happens in "ghost" cells is a speculation. What I observe is that the 33th cell is a NAN and caused this error, so I speculate 33 = 32 + 1 is the ghost cell. I'm not sure if you do have a ghost cell when running it on a single core on CPU. The domain is resolved with 128 grids in this problem.

To Reproduce
Steps to reproduce the behavior:

1. In development branch, set radiationReconstructionOrder_ = 2 and reconstructionOrder_ = 2 in the RadTube test, compile it in Debug mode, and run it.
2. The program immediately fail with "Erroneous arithmetic operation". This error occurred inside HydroSystem<problem_t>::FlattenShocks

Additional context
Add any other context about the problem here.