gh-99708: fix bug where compiler crashes on if expression with an empty body block #99732
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Fixes #99708.
The crash comes from a cleanup sequence where we call
eliminate_empty_basic_blocks()
followed byremove_redundant_nops()
. Later we assert that there are no empty blocks, but removing a redundant NOP can create an empty basic block.I don't think that removing empty blocks can create new redundant NOPs. So this PR reverses the order, and add a debug assertion afterwards that there are no redundant NOPs.