When APM is used without calling `ApplyConfig()` and the level estimator sub-module, which is disabled by default (see [1]), is used, APM crashes because the enabled config flag is true, but the unique pointer object is unset. [1] https://source.chromium.org/chromium/chromium/src/+/main:third_party/webrtc/modules/audio_processing/include/audio_processing.h;l=391?q=include%2Faudio_processing.h Bug: webrtc:7494 Change-Id: I482a9aa4f6a0a56793769674aba7b2661330bb14 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/235375 Reviewed-by: Per Åhgren <peah@webrtc.org> Commit-Queue: Alessio Bazzica <alessiob@webrtc.org> Cr-Commit-Position: refs/heads/main@{#35230}