_apply_sampler turns a cross-family sampler into a 400 that explains itself:
flow-matching and DDPM schedulers parameterise the trajectory differently, so
one cannot stand in for the other. The acceleration config applied its
`scheduler` with no such check, and a card is exactly where that mistake gets
made and never noticed.

Krea-2-Turbo's entry asked for EulerDiscreteScheduler on a flow-matching
model. The swap succeeded silently and the generation then died with

    EulerDiscreteScheduler.set_timesteps() got an unexpected keyword
    argument 'mu'

which names neither the card nor the model, arrives from inside diffusers, and
reads like a library bug. Now it is refused and logged, naming both
schedulers, and the model keeps its own -- acceleration is an optimisation and
has always been allowed to decline.

One set of family names, imported by both paths, so they cannot drift.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014T3rZnLhydX9QqUcfBbqLu