Overwrite default config with CLI input even when the input value is …

…considered as empty

This change will fix two issues:
1. When CLI sets a flag to an empty value in Go, e.g. 0 as to Uint64, the flag will be skipped and never set correctly. This problem could be solved by using option "WithOverwriteWithEmptyValue" when merge two configs.
2. The default non-empty value in server config will be overwritten to an empty value after flag initialization. This problem is solved by explicitly providing default value to all flags that have a default value option.

internal/cli/server/config.go

@@ -956,14 +956,9 @@ func (c *Config) buildNode() (*node.Config, error) {
 
 func (c *Config) Merge(cc ...*Config) error {
  for _, elem := range cc {
- if err := mergo.Merge(c, elem, mergo.WithOverride, mergo.WithAppendSlice); err != nil {
+ if err := mergo.Merge(c, elem, mergo.WithOverwriteWithEmptyValue, mergo.WithAppendSlice); err != nil {
  return fmt.Errorf("failed to merge configurations: %v", err)
  }
-
- // override max peers
- if elem.P2P.MaxPeers == 0 {
- c.P2P.MaxPeers = 0
- }
  }
  return nil
 }

internal/cli/server/config_test.go

@@ -54,14 +54,11 @@ func TestConfigMerge(t *testing.T) {
  }
  expected := &Config{
  Chain: "1",
- NoSnapshot: true,
+ NoSnapshot: false,
  RequiredBlocks: map[string]string{
  "a": "b",
  "b": "c",
  },
- TxPool: &TxPoolConfig{
- LifeTime: 5 * time.Second,
- },
  P2P: &P2PConfig{
  MaxPeers: 10,
  Discovery: &P2PDiscovery{