add error type instead of expect

Author: AmbientTea

toolkit/committee-selection/authority-selection-inherents/src/ariadne_inherent_data_provider.rs

@@ -62,10 +62,9 @@ impl AriadneInherentDataProvider {
 			timestamp_millis,
 		)?;
 
-		let data_epoch = offset_data_epoch(&for_mc_epoch).expect(&format!(
-			"Could not apply data offset to MC epoch {} for authority selection; this is caused either by misconfiguration or a bug.",
-			for_mc_epoch.0,
-		));
+		let data_epoch = offset_data_epoch(&for_mc_epoch).map_err(|offset| {
+			InherentProviderCreationError::McEpochOffsetError(offset, for_mc_epoch)
+		})?;
 
 		// We could accept mc_reference at last slot of data_epoch, but calculations are much easier like that.
 		// Additionally, in current implementation, the inequality below is always true, thus there is no need to make it more accurate.
@@ -100,6 +99,10 @@ pub enum InherentProviderCreationError {
 	/// Couldn't convert timestamp to main chain epoch.
 	#[error("Couldn't convert timestamp to main chain epoch: {0}")]
 	McEpochDerivationError(#[from] sidechain_domain::mainchain_epoch::EpochDerivationError),
+	#[error(
+		"Could not apply data offset of {0} to MC epoch {1:?} for authority selection; this is caused either by a node misconfiguration or a bug."
+	)]
+	McEpochOffsetError(u32, McEpochNumber),
 	/// Runtime API call failed.
 	#[error("Runtime API call failed: {0}")]
 	ApiError(#[from] sp_api::ApiError),