Offence reporting returns a result (#5082)

* Offence reporting returns a result

* Bump spec_version

* Use unwrap instead of assertions

* Fix more review grumbles

substrate/bin/node/runtime/src/lib.rs

@@ -82,7 +82,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	// and set impl_version to 0. If only runtime
 	// implementation changes and behavior does not, then leave spec_version as
 	// is and increment impl_version.
-	spec_version: 226,
+	spec_version: 227,
 	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 };