How can i fix this error ? Attempt to get argmax of an empty sequence

Question

I was trying to explore data using Python and this is my code :

import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns

df = pd.read_csv('transactions-pet_store-clean.csv')

common_category_cat = df[df['Product_Line'] == 'Cat'].groupby('Product_Category')['Quantity'].sum().idxmax()
common_category_dog = df[df['Product_Line'] == 'Dog'].groupby('Product_Category')['Quantity'].sum().idxmax()

# Displaying the results
print("Common category for cats:", common_category_cat)
print("Common category for dogs:", common_category_dog)`

When trying to run the code , these errrors occured :

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-1-3ef163bcf298> in <module>
      5 df = pd.read_csv('transactions-pet_store-clean.csv')
      6 
----> 7 common_category_cat = df[df['Product_Line'] == 'Cat'].groupby('Product_Category')['Quantity'].sum().idxmax()
      8 common_category_dog = df[df['Product_Line'] == 'Dog'].groupby('Product_Category')['Quantity'].sum().idxmax()

/opt/conda/lib/python3.7/site-packages/pandas/core/series.py in idxmax(self, axis, skipna, *args, **kwargs)
   2108         """
   2109         skipna = nv.validate_argmax_with_skipna(skipna, args, kwargs)
-> 2110         i = nanops.nanargmax(com.values_from_object(self), skipna=skipna)
   2111         if i == -1:
   2112             return np.nan

/opt/conda/lib/python3.7/site-packages/pandas/core/nanops.py in _f(*args, **kwargs)
     67             try:
     68                 with np.errstate(invalid="ignore"):
---> 69                     return f(*args, **kwargs)
     70             except ValueError as e:
     71                 # we want to transform an object array

/opt/conda/lib/python3.7/site-packages/pandas/core/nanops.py in nanargmax(values, axis, skipna, mask)
    873         values, True, fill_value_typ="-inf", mask=mask
    874     )
--> 875     result = values.argmax(axis)
    876     result = _maybe_arg_null_out(result, axis, mask, skipna)
    877     return result

ValueError: attempt to get argmax of an empty sequence`