fix(storage): initialize file to an empty JSON

It will avoir error message like `time="2022-11-14T01:40:49Z" level=error msg="error loading sessionsEOF"`

app/storage/file.go

@@ -33,6 +33,16 @@ func NewFileStorage(config config.Storage) (Storage, error) {
 		}
 		defer file.Close()
 
+		stats, err := file.Stat()
+		if err != nil {
+			return nil, err
+		}
+
+		// Initialize file to an empty JSON3
+		if stats.Size() == 0 {
+			file.WriteString("{}")
+		}
+
 		log.Infof("initialized storage to %s", config.File)
 	} else {
 		log.Warn("no storage configuration provided. all states will be lost upon exit")

docs/guides/code-server-traefik-kubernetes.md

@@ -189,7 +189,6 @@
     time="2022-11-14T01:40:49Z" level=info msg="(version=1.1.1, branch=HEAD, revision=a913bc2a3b0f4aca5b9ac7ddc9af5428ef411dba)"
     time="2022-11-14T01:40:49Z" level=info msg="using provider \"kubernetes\""
     time="2022-11-14T01:40:49Z" level=info msg="initialized storage to /etc/sablier/state.json"
-    time="2022-11-14T01:40:49Z" level=error msg="error loading sessionsEOF"
     time="2022-11-14T01:40:49Z" level=info msg="server listening :10000"
     ```