Remove spurious debug_assert! (paritytech#9603)

Author: tomaka

Cargo.lock

@@ -31,3 +31,5 @@ parking_lot = "0.11.1"
 derive_more = "0.99.2"
 prometheus-endpoint = { package = "substrate-prometheus-endpoint", path = "../../../utils/prometheus", version = "0.9.0"}
 async-trait = "0.1.50"
+tokio = { version = "1.10.1", features = ["sync"] }
+tokio-stream = "0.1.7"