feat: return a not found response if requested a wrong API endpoints

controller/relay.go

@@ -398,3 +398,15 @@ func RelayNotImplemented(c *gin.Context) {
 		"error": err,
 	})
 }
+
+func RelayNotFound(c *gin.Context) {
+	err := OpenAIError{
+		Message: fmt.Sprintf("API not found: %s:%s", c.Request.Method, c.Request.URL.Path),
+		Type:    "one_api_error",
+		Param:   "",
+		Code:    "api_not_found",
+	}
+	c.JSON(http.StatusOK, gin.H{
+		"error": err,
+	})
+}