fix: url with variable not work (#12452)

Author: hjlarry

api/core/workflow/nodes/http_request/executor.py

@@ -82,12 +82,6 @@ def __init__(
                 node_data.authorization.config.api_key
             ).text
 
-        # check if node_data.url is a valid URL
-        if not node_data.url:
-            raise InvalidURLError("url is required")
-        if not node_data.url.startswith(("http://", "https://")):
-            raise InvalidURLError("url should start with http:// or https://")
-
         self.url: str = node_data.url
         self.method = node_data.method
         self.auth = node_data.authorization
@@ -114,6 +108,12 @@ def _initialize(self):
     def _init_url(self):
         self.url = self.variable_pool.convert_template(self.node_data.url).text
 
+        # check if url is a valid URL
+        if not self.url:
+            raise InvalidURLError("url is required")
+        if not self.url.startswith(("http://", "https://")):
+            raise InvalidURLError("url should start with http:// or https://")
+
     def _init_params(self):
         """
         Almost same as _init_headers(), difference: