Don't report RewardType::Fee when none was awarded

runtime/src/bank.rs

@@ -1484,6 +1484,7 @@ impl Bank {
             );
 
             let post_balance = self.deposit(&self.collector_id, unburned);
+            if unburned != 0 {
                 self.rewards.write().unwrap().push((
                     self.collector_id,
                     RewardInfo {
@@ -1492,6 +1493,7 @@ impl Bank {
                         post_balance,
                     },
                 ));
+            }
             self.capitalization.fetch_sub(burned, Relaxed);
         }
     }