fix: log error if FrankenPHP is not properly started (#1314)

Co-authored-by: Alliballibaba <[email protected]>

caddy/caddy.go

@@ -318,10 +318,14 @@ func (f FrankenPHPModule) ServeHTTP(w http.ResponseWriter, r *http.Request, _ ca
 	)
 
 	if err != nil {
-		return err
+		return caddyhttp.Error(http.StatusInternalServerError, err)
+	}
+
+	if err = frankenphp.ServeHTTP(w, fr); err != nil {
+		return caddyhttp.Error(http.StatusInternalServerError, err)
 	}
 
-	return frankenphp.ServeHTTP(w, fr)
+	return nil
 }
 
 // UnmarshalCaddyfile implements caddyfile.Unmarshaler.

frankenphp.go

@@ -62,6 +62,7 @@ var (
 	MainThreadCreationError     = errors.New("error creating the main thread")
 	RequestContextCreationError = errors.New("error during request context creation")
 	ScriptExecutionError        = errors.New("error during PHP script execution")
+	NotRunningError             = errors.New("FrankenPHP is not running. For proper configuration visit: https://frankenphp.dev/docs/config/#caddyfile-config")
 
 	requestChan chan *http.Request
 	isRunning   bool
@@ -454,6 +455,10 @@ func updateServerContext(thread *phpThread, request *http.Request, create bool,
 
 // ServeHTTP executes a PHP script according to the given context.
 func ServeHTTP(responseWriter http.ResponseWriter, request *http.Request) error {
+	if !isRunning {
+		return NotRunningError
+	}
+
 	if !requestIsValid(request, responseWriter) {
 		return nil
 	}