no collator shall be left unpaid

pallets/parachain-staking/src/lib.rs

@@ -2917,7 +2917,25 @@ pub mod pallet {
 
 			let old_round = round - 1;
 			// Get total collator staking number of round that is ending
-			let (in_reads, total_stake) = Self::get_total_collator_staking_num(old_round);
+			let (in_reads, mut total_stake) = Self::get_total_collator_staking_num(old_round);
+
+			// Total stake cannot be zero
+			// We expect this is the case when runtime upgrade for token-economy-v2 is done.
+			// TODO this case can be removed in later upgrades.
+			if total_stake.is_zero() {
+				// there will be only 1 unfortunate author, as we force new round in runtime upgrade
+				CollatorBlocks::<T>::iter_prefix(old_round).for_each(|(collator, num)| {
+					if let Some(state) = CandidatePool::<T>::get(collator.clone()) {
+						let collator_total = T::CurrencyBalance::from(num)
+							.checked_mul(&state.total)
+							.unwrap_or_else(Zero::zero);
+						total_stake = total_stake.saturating_add(collator_total);
+						reads = reads.saturating_add(Weight::from_parts(1_u64, 0));
+					};
+					reads = reads.saturating_add(Weight::from_parts(1_u64, 0));
+				});
+			}
+
 			// Get total issuance of round that is ending
 			let (issuance_weight, total_issuance) = Self::pot_issuance();
 			reads = reads.saturating_add(in_reads).saturating_add(issuance_weight);