Llama index embeddings not generated: "Embeddings have been explicitly disabled. Using MockEmbedding."

Question

I'm learning how to use LlamaIndex for retrieval augmented generation (RAG), i.e. Making chatbots that can answer questions based on documents containing a mixture of text, tables, images, etc. I'm trying to follow a tutorial running this notebook in Colab. When running this block:

import os
import pickle

raw_nodes_2021 = node_parser.get_nodes_from_documents(docs_2021)
pickle.dump(raw_nodes_2021, open("2021_nodes.pkl", "wb"))

it prints the following output:

Embeddings have been explicitly disabled. Using MockEmbedding.
0it [00:00, ?it/s]

As a result, the node_mappings_2021 variable is an empty dict. What is missing? How can I enable Embeddings?

EDIT: To reproduce the error run this notebook in Colab