fix: avoid scheduling an instance refresh if the context is done

internal/alloydb/instance.go

@@ -280,6 +280,13 @@ func (i *Instance) scheduleRefresh(d time.Duration) *refreshOperation {
 		// result and schedule a new refresh
 		i.resultGuard.Lock()
 		defer i.resultGuard.Unlock()
+
+		// instance has been closed, don't schedule anything
+		if i.ctx.Err() != nil {
+			i.cur = r
+			return
+		}
+
 		// if failed, scheduled the next refresh immediately
 		if r.err != nil {
 			i.next = i.scheduleRefresh(0)
@@ -297,12 +304,6 @@ func (i *Instance) scheduleRefresh(d time.Duration) *refreshOperation {
 		// Update the current results, and schedule the next refresh in
 		// the future
 		i.cur = r
-		select {
-		case <-i.ctx.Done():
-			// instance has been closed, don't schedule anything
-			return
-		default:
-		}
 		t := refreshDuration(time.Now(), i.cur.result.expiry)
 		i.next = i.scheduleRefresh(t)
 	})