Auto assign server_id for bootstrapped config files.

This commit fixes an issue where the server may start up without
a "server_id" assigned, which in turn will cause a follower to
be unable to connect.

This issues is caused by including a pre-generated "data/config"
file that does not include the "server_id" field.

internal/server/config.go

@@ -71,14 +71,13 @@ func loadConfig(path string) (*Config, error) {
 	var json string
 	data, err := ioutil.ReadFile(path)
 	if err != nil {
-		if os.IsNotExist(err) {
-			json = `{"` + ServerID + `":"` + randomKey(16) + `"}`
-		} else {
+		if !os.IsNotExist(err) {
 			return nil, err
 		}
 	} else {
 		json = string(data)
 	}
+
 	config := &Config{
 		path:            path,
 		_followHost:     gjson.Get(json, FollowHost).String(),
@@ -96,6 +95,10 @@ func loadConfig(path string) (*Config, error) {
 		_logConfig:      gjson.Get(json, LogConfig).String(),
 	}
 
+	if config._serverID == "" {
+		config._serverID = randomKey(16)
+	}
+
 	// load properties
 	if err := config.setProperty(RequirePass, config._requirePassP, true); err != nil {
 		return nil, err
@@ -191,8 +194,10 @@ func (config *Config) write(writeProperties bool) {
 	if config._logConfigP != "" {
 		var lcfg map[string]interface{}
 		json.Unmarshal([]byte(config._logConfig), &lcfg)
+		if len(lcfg) > 0 {
 			m[LogConfig] = lcfg
 		}
+	}
 	data, err := json.MarshalIndent(m, "", "\t")
 	if err != nil {
 		panic(err)