[llvm] [NFC][Sink] Change runtime checks to asserts (PR #137354)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

Nice catch, looks like this is a leftover from an old implementation prior to https://github.com/llvm/llvm-project/commit/f2284e3405d87143b2478f28b8045bef84953c91.

https://github.com/llvm/llvm-project/pull/137354