avoid a crash in crawler when lifecycle is not initialized (#11170)

Bonus for static buffers use bytes.NewReader instead of
bytes.NewBuffer, to use a more reader friendly implementation

cmd/metacache-stream_test.go

@@ -33,7 +33,7 @@ func loadMetacacheSample(t testing.TB) *metacacheReader {
 	if err != nil {
 		t.Fatal(err)
 	}
-	r, err := newMetacacheReader(bytes.NewBuffer(b))
+	r, err := newMetacacheReader(bytes.NewReader(b))
 	if err != nil {
 		t.Fatal(err)
 	}