Removed _core property on SmartDataframe that causes maximum recursion depth exceeded

[andeplane]

I ran into RecursionError: maximum recursion depth exceeded when using SmartDataframe and found the issue is caused by a call to __getattr__ trying to access _core which does not exist, but it calls __getattr__ repeatedly.

There may be something I don't understand in the code here, and that this has a reason to exist, but this solved my problems.

To reproduce the problem, create a smart data frame with e.g.

import os
import pandas as pd
from pandasai import SmartDataframe

# Sample DataFrame
sales_by_country = pd.DataFrame({
    "country": ["United States", "United Kingdom", "France", "Germany", "Italy", "Spain", "Canada", "Australia", "Japan", "China"],
    "revenue": [5000, 3200, 2900, 4100, 2300, 2100, 2500, 2600, 4500, 7000]
})

# By default, unless you choose a different LLM, it will use BambooLLM.
# You can get your free API key signing up at https://pandabi.ai (you can also configure it in your .env file)
os.environ["PANDASAI_API_KEY"] = "<insert_key>"

df = SmartDataframe(sales_by_country)
df.anyproperty

to see that it throws this error.

• Closes #xxxx (Replace xxxx with the GitHub issue number).
• Tests added and passed if fixing a bug or adding a new feature.
• All code checks passed.