Fix crc64 unit test

db.go

@@ -1485,6 +1485,12 @@ func (db *DB) CRC64() (uint64, Pos, error) {
 	db.mu.Lock()
 	defer db.mu.Unlock()
 
+	if err := db.init(); err != nil {
+		return 0, Pos{}, err
+	} else if db.db == nil {
+		return 0, Pos{}, os.ErrNotExist
+	}
+
 	// Force a RESTART checkpoint to ensure the database is at the start of the WAL.
 	if err := db.checkpoint(CheckpointModeRestart); err != nil {
 		return 0, Pos{}, err

db_test.go

@@ -137,8 +137,8 @@ func TestDB_CRC64(t *testing.T) {
 			t.Fatal(err)
 		} else if chksum1, _, err := db.CRC64(); err != nil {
 			t.Fatal(err)
-		} else if chksum0 != chksum1 {
-			t.Fatal("expected equal checksum after WAL change")
+		} else if chksum0 == chksum1 {
+			t.Fatal("expected different checksum event after WAL change")
 		}
 
 		// Checkpoint change into database. Checksum should change.