Fix web-base loader (#11135)

Fix initialization

https://github.com/langchain-ai/langchain/issues/11095

libs/langchain/langchain/document_loaders/web_base.py

@@ -76,10 +76,15 @@ class WebBaseLoader(BaseLoader):
             )
         if web_paths:
             self.web_paths = list(web_paths)
+        elif isinstance(web_path, str):
+            self.web_paths = [web_path]
         elif isinstance(web_path, Sequence):
             self.web_paths = list(web_path)
         else:
-            self.web_paths = [web_path]
+            raise TypeError(
+                f"web_path must be str or Sequence[str] got ({type(web_path)}) or"
+                f" web_paths must be Sequence[str] got ({type(web_paths)})"
+            )
         self.requests_per_second = requests_per_second
         self.default_parser = default_parser
         self.requests_kwargs = requests_kwargs or {}

libs/langchain/tests/unit_tests/document_loaders/test_web_base.py

@@ -11,3 +11,11 @@ class TestWebBaseLoader:
         url = "https://www.example.com"
         loader = WebBaseLoader(url, header_template=header_template)
         assert loader.session.headers["User-Agent"] == user_specified_user_agent
+
+    def test_web_path_parameter(self) -> None:
+        web_base_loader = WebBaseLoader(web_paths=["https://www.example.com"])
+        assert web_base_loader.web_paths == ["https://www.example.com"]
+        web_base_loader = WebBaseLoader(web_path=["https://www.example.com"])
+        assert web_base_loader.web_paths == ["https://www.example.com"]
+        web_base_loader = WebBaseLoader(web_path="https://www.example.com")
+        assert web_base_loader.web_paths == ["https://www.example.com"]