refactor: simplify Channel waiter resuming and removal

Author: Brandon Schoenfeld

Sources/AsyncDataLoader/Channel.swift

@@ -12,12 +12,10 @@ extension Channel {
         if result == nil {
             result = value
 
-            for waiter in waiters {
-                waiter.resume(returning: value)
+            while let waiter = waiters.popLast() {
+                waiter.resume(returning: success)
             }
 
-            waiters.removeAll()
-
             return false
         }
 
@@ -29,12 +27,10 @@ extension Channel {
         if self.failure == nil {
             self.failure = failure
 
-            for waiter in waiters {
+            while let waiter = waiters.popLast() {
                 waiter.resume(throwing: failure)
             }
 
-            waiters.removeAll()
-
             return false
         }