blockchain: TimeSource is required.

blockchain/chain.go

@@ -1683,6 +1683,9 @@ func New(config *Config) (*BlockChain, error) {
 	if config.ChainParams == nil {
 		return nil, AssertError("blockchain.New chain parameters nil")
 	}
+	if config.TimeSource == nil {
+		return nil, AssertError("blockchain.New timesource is nil")
+	}
 
 	// Generate a checkpoint by height map from the provided checkpoints.
 	params := config.ChainParams

cmd/findcheckpoint/findcheckpoint.go

@@ -153,6 +153,7 @@ func main() {
 	chain, err := blockchain.New(&blockchain.Config{
 		DB:          db,
 		ChainParams: activeNetParams,
+		TimeSource:  blockchain.NewMedianTime(),
 	})
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "failed to initialize chain: %v\n", err)