core/filtermaps: fix hang in tests

Since the index can now be disabled at runtime, it is no longer safe
to just check the disabled field once.

core/filtermaps/indexer.go

@@ -137,16 +137,17 @@ func (f *FilterMaps) SetBlockProcessing(blockProcessing bool) {
 // WaitIdle blocks until the indexer is in an idle state while synced up to the
 // latest targetView.
 func (f *FilterMaps) WaitIdle() {
-	if f.disabled {
-		f.closeWg.Wait()
-		return
-	}
 	for {
 		ch := make(chan bool)
-		f.waitIdleCh <- ch
+		select {
+		case f.waitIdleCh <- ch:
 			if <-ch {
 				return
 			}
+		case <-f.disabledCh:
+			f.closeWg.Wait()
+			return
+		}
 	}
 }