Using faiss.from_documents require tokenizer pad_token
Labels: name: area: embeddings, name: auto:bug

### Checked other resources

- [X] I added a very descriptive title to this issue.
- [X] I searched the LangChain documentation with the integrated search.
- [X] I used the GitHub search to find a similar question and didn't find it.

### Example Code

```
embeddings = HuggingFaceEmbeddings(
    model_name="mistralai/Mistral-7B-v0.1",     # Provide the pre-trained model's path
)
cache_embeddings = CacheBackedEmbeddings.from_bytes_store(embeddings, cached_dir)
vectorstore = FAISS.from_documents(docs, cache_embeddings)

```
I use this code. 
I met this error.
Why occur this occur? I look around all. I can't fix ti. so Sad ㅠㅠㅠ
Could you explain me how to get fix it?

 
```
ValueError                                Traceback (most recent call last)
Cell In[8], [line 1](vscode-notebook-cell:?execution_count=8&line=1)
----> [1](vscode-notebook-cell:?execution_count=8&line=1) vectorstore = FAISS.from_documents(docs, cache_embeddings)
      [3](vscode-notebook-cell:?execution_count=8&line=3) retriver = vectorstore.as_retriever(reduce_k_below_max_tokens=True)
      [4](vscode-notebook-cell:?execution_count=8&line=4) # retriver = vectorstore.as_retriever()

File [~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_core/vectorstores.py:508](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_core/vectorstores.py:508), in VectorStore.from_documents(cls, documents, embedding, **kwargs)
    [506](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_core/vectorstores.py:506) texts = [d.page_content for d in documents]
    [507](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_core/vectorstores.py:507) metadatas = [d.metadata for d in documents]
--> [508](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_core/vectorstores.py:508) return cls.from_texts(texts, embedding, metadatas=metadatas, **kwargs)

File [~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:913](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:913), in FAISS.from_texts(cls, texts, embedding, metadatas, ids, **kwargs)
    [886](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:886) @classmethod
    [887](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:887) def from_texts(
    [888](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:888)     cls,
   (...)
    [893](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:893)     **kwargs: Any,
    [894](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:894) ) -> FAISS:
    [895](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:895)     """Construct FAISS wrapper from raw documents.
    [896](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:896) 
    [897](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:897)     This is a user friendly interface that:
   (...)
    [911](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:911)             faiss = FAISS.from_texts(texts, embeddings)
    [912](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/langchain_community/vectorstores/faiss.py:912)     """
...
   (...)
   [2719](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/transformers/tokenization_utils_base.py:2719)     and (max_length % pad_to_multiple_of != 0)
   [2720](https://vscode-remote+ssh-002dremote-002bssh-002eddapp-002eio.vscode-resource.vscode-cdn.net/home/datadriven/ds.kang/rag/~/anaconda3/envs/rag/lib/python3.11/site-packages/transformers/tokenization_utils_base.py:2720) ):

ValueError: Asking to pad but the tokenizer does not have a padding token. Please select a token to use as `pad_token` `(tokenizer.pad_token = tokenizer.eos_token e.g.)` or add a new pad token via `tokenizer.add_special_tokens({'pad_token': '[PAD]'})`

```

### Description

I use this code. 
I met this error.
Why occur this occur? I look around all. I can't fix ti. so Sad ㅠㅠㅠ
Could you explain me how to get fix it?

### System Info

langchain                0.1.0
langchain-community      0.0.12
langchain-core           0.1.10
langsmith                0.0.80

### Related Components

- [ ] LLMs/Chat Models
- [X] Embedding Models
- [ ] Prompts / Prompt Templates / Prompt Selectors
- [ ] Output Parsers
- [ ] Document Loaders
- [ ] Vector Stores / Retrievers
- [ ] Memory
- [ ] Agents / Agent Executors
- [ ] Tools / Toolkits
- [ ] Chains
- [ ] Callbacks/Tracing
- [ ] Async