lite2: return if there are no headers in RemoveNoLongerTrustedHeaders (#4378)

lite2/client.go

@@ -960,11 +960,14 @@ func (c *Client) removeNoLongerTrustedHeadersRoutine() {
 // Exposed for testing.
 func (c *Client) RemoveNoLongerTrustedHeaders(now time.Time) {
 	// 1) Get the oldest height.
-	oldestHeight, err := c.trustedStore.FirstSignedHeaderHeight()
+	oldestHeight, err := c.FirstTrustedHeight()
 	if err != nil {
 		c.logger.Error("can't get first trusted height", "err", err)
 		return
 	}
+	if oldestHeight == -1 { // no headers yet => wait
+		return
+	}
 
 	// 2) Get the latest height.
 	latestHeight, err := c.LastTrustedHeight()
@@ -972,6 +975,9 @@ func (c *Client) RemoveNoLongerTrustedHeaders(now time.Time) {
 		c.logger.Error("can't get last trusted height", "err", err)
 		return
 	}
+	if latestHeight == -1 { // no headers yet => wait
+		return
+	}
 
 	// 3) Remove all headers that are outside of the trusting period.
 	for height := oldestHeight; height <= latestHeight; height++ {

lite2/client_test.go

@@ -307,6 +307,12 @@ func TestClientRemovesNoLongerTrustedHeaders(t *testing.T) {
 		dbs.New(dbm.NewMemDB(), chainID),
 		Logger(log.TestingLogger()),
 	)
+
+	assert.NotPanics(t, func() {
+		now := bTime.Add(4 * time.Hour).Add(1 * time.Second)
+		c.RemoveNoLongerTrustedHeaders(now)
+	})
+
 	require.NoError(t, err)
 	err = c.Start()
 	require.NoError(t, err)