Streaming Read: Segfault on Close w/o Explicit Flush

I am trying to read data from a file. I create a `Series` and the iteration via `readIters = series->readIterations()` and `iter = *readIters.begin()`. I schedule the reads via `loadChunk`, passing pointers to AMReX-allocated data structures.

I then tried to perform the reads via `iter.close()`. This lead to a segfault.

I can avoid the segfault by calling `series->flush()` before closing the iteration.