Bug fixes and error handling in Redis - Vectorstore (#4932)

# Bug fixes in Redis - Vectorstore (Added the version of redis to the
error message and removed the cls argument from a classmethod)


Co-authored-by: Tyler Hutcherson <tyler.hutcherson@redis.com>

langchain/vectorstores/redis.py

@@ -56,8 +56,9 @@ def _check_redis_module_exist(client: RedisType, required_modules: List[dict]) -
             return
     # otherwise raise error
     error_message = (
-        "You must add the RediSearch (>= 2.4) module from Redis Stack. "
-        "Please refer to Redis Stack docs: https://redis.io/docs/stack/"
+        "Redis cannot be used as a vector database without RediSearch >=2.4"
+        "Please head to https://redis.io/docs/stack/search/quick_start/"
+        "to know more about installing the RediSearch module within Redis Stack."
     )
     logging.error(error_message)
     raise ValueError(error_message)
@@ -126,7 +127,7 @@ def __init__(
         except ImportError:
             raise ValueError(
                 "Could not import redis python package. "
-                "Please install it with `pip install redis`."
+                "Please install it with `pip install redis>=4.1.0`."
             )
 
         self.embedding_function = embedding_function
@@ -358,7 +359,7 @@ def _similarity_search_with_relevance_scores(
 
     @classmethod
     def from_texts_return_keys(
-        cls: Type[Redis],
+        cls,
         texts: List[str],
         embedding: Embeddings,
         metadatas: Optional[List[dict]] = None,