fix(loki): pass missing config error to user

Missing config errors are handled at the library level. Our own check mitigated
this and causes loki to SEGFAULT later on

Author: tombrk

cmd/loki/main.go

@@ -43,11 +43,9 @@ func main() {
 
 	util.InitLogger(&cfg.Server)
 
-	if configFile != "" {
-		if err := helpers.LoadConfig(configFile, &cfg); err != nil {
-			level.Error(util.Logger).Log("msg", "error loading config", "filename", configFile, "err", err)
-			os.Exit(1)
-		}
+	if err := helpers.LoadConfig(configFile, &cfg); err != nil {
+		level.Error(util.Logger).Log("msg", "error loading config", "filename", configFile, "err", err)
+		os.Exit(1)
 	}
 
 	// Re-init the logger which will now honor a different log level set in cfg.Server