diff --git a/client/executor/src/integration_tests/mod.rs b/client/executor/src/integration_tests/mod.rs
index 3d04d5cc01547..c8b763a6b1936 100644
--- a/client/executor/src/integration_tests/mod.rs
+++ b/client/executor/src/integration_tests/mod.rs
@@ -766,5 +766,5 @@ fn panic_in_spawned_instance_panics_on_joining_its_result(wasm_method: WasmExecu
 	).unwrap_err();
 
 	dbg!(&error_result);
-	assert!(format!("{}", error_result).contains("Spawned task panicked"));
+	assert!(format!("{}", error_result).contains("Spawned task"));
 }
diff --git a/client/executor/src/native_executor.rs b/client/executor/src/native_executor.rs
index 3cdc34939b38d..f05b49a5246c7 100644
--- a/client/executor/src/native_executor.rs
+++ b/client/executor/src/native_executor.rs
@@ -355,7 +355,8 @@ impl sp_io::RuntimeSpawn for RuntimeInstanceSpawn {
 					// pool of instances should be used.
 					//
 					// https://github.com/paritytech/substrate/issues/7354
-					let instance = module.new_instance().expect("Failed to create new instance");
+					let instance = module.new_instance()
+						.expect("Failed to create new instance from module");
 
 					instance.call(
 						InvokeMethod::TableWithWrapper { dispatcher_ref, func },
@@ -364,10 +365,15 @@ impl sp_io::RuntimeSpawn for RuntimeInstanceSpawn {
 				}
 			);
 
-			// If execution is panicked, the `join` in the original runtime code will panic as well,
-			// since the sender is dropped without sending anything.
-			if let Ok(output) = result {
-				let _ = sender.send(output);
+			match result {
+				Ok(output) => {
+					let _ = sender.send(output);
+				},
+				Err(error) => {
+					// If execution is panicked, the `join` in the original runtime code will panic as well,
+					// since the sender is dropped without sending anything.
+					log::error!("Call error in spawned task: {:?}", error);
+				},
 			}
 		}));
 
@@ -403,13 +409,16 @@ impl RuntimeInstanceSpawn {
 			.map(move |task_ext| Self::new(module, task_ext.clone()))
 	}
 
-	fn register_on_externalities(module: Arc<dyn WasmModule>) {
+	/// Register new `RuntimeSpawnExt` on current externalities.
+	///
+	/// This extensions will spawn instances from provided `module`.
+	pub fn register_on_externalities(module: Arc<dyn WasmModule>) {
 		sp_externalities::with_externalities(
 			move |mut ext| {
 				if let Some(runtime_spawn) =
 					Self::with_externalities_and_module(module.clone(), ext)
 				{
-					if let Err(e) = ext.register_extension::<RuntimeSpawnExt>(
+					if let Err(e) = ext.register_extension(
 						RuntimeSpawnExt(Box::new(runtime_spawn))
 					) {
 						trace!(
diff --git a/client/executor/wasmtime/src/instance_wrapper.rs b/client/executor/wasmtime/src/instance_wrapper.rs
index c93063f7692be..14493266d9e43 100644
--- a/client/executor/wasmtime/src/instance_wrapper.rs
+++ b/client/executor/wasmtime/src/instance_wrapper.rs
@@ -112,7 +112,11 @@ impl EntryPoint {
 					wasmtime::Val::I32(data_len),
 				])
 			},
-		}).map(|results| results[0].unwrap_i64() as u64)
+		})
+			.map(|results| 
+				// the signature is checked to have i64 return type
+				results[0].unwrap_i64() as u64
+			)
 	}
 
 	pub fn direct(func: wasmtime::Func) -> std::result::Result<Self, &'static str> {
@@ -121,7 +125,7 @@ impl EntryPoint {
 				Ok(Self { func, call_type: EntryPointType::Direct })
 			}
 			_ => {
-				Err("Invalid signature")
+				Err("Invalid signature for direct entry point")
 			}
 		}
 	}
@@ -135,7 +139,7 @@ impl EntryPoint {
 				Ok(Self { func: dispatcher, call_type: EntryPointType::Wrapped(func) })
 			},
 			_ => {
-				Err("Invalid signature")
+				Err("Invalid signature for wrapped entry point")
 			}
 		}
 	}
diff --git a/primitives/io/src/lib.rs b/primitives/io/src/lib.rs
index c3b10a8592e75..44b748942da56 100644
--- a/primitives/io/src/lib.rs
+++ b/primitives/io/src/lib.rs
@@ -1273,6 +1273,7 @@ trait RuntimeTasks {
 	/// Wasm host function for spawning task.
 	///
 	/// This should not be used directly. Use `sp_io::tasks::spawn` instead.
+	#[cfg_attr(feature = "std", allow(dead_code))]
 	fn spawn(&mut self, dispatcher_ref: u32, entry: u32, payload: Vec<u8>) -> u64 {
 		let runtime_spawn = self.extension::<RuntimeSpawnExt>()
 			.expect("Cannot spawn without dynamic runtime dispatcher (RuntimeSpawnExt)");
@@ -1282,6 +1283,7 @@ trait RuntimeTasks {
 	/// Wasm host function for joining a task.
 	///
 	/// This should not be used directly. Use `join` of `sp_io::tasks::spawn` result instead.
+	#[cfg_attr(feature = "std", allow(dead_code))]
 	fn join(&mut self, handle: u64) -> Vec<u8> {
 		let runtime_spawn = self.extension::<RuntimeSpawnExt>()
 			.expect("Cannot spawn without dynamic runtime dispatcher (RuntimeSpawnExt)");