ASSERT(sum.productivity_cpu_percent >= 0)

While investigating #19417 (closed) I hit this assert in rts/Stats.c: https://gitlab.haskell.org/ghc/ghc/-/blob/ghc-8.10.4-release/rts/Stats.c#L1407

Environment

GHC version used: 8.10.4 with the debug runtime

Optional:

Operating System: redhat
System Architecture: x86_64

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