AssertionError: Total area is zero in defuzzification!

[yashguptaab99]

---

AssertionError Traceback (most recent call last)
in ()
63
64 # Calculate defuzzified result
---> 65 op = fuzz.defuzz(x_op, aggregated, 'centroid')
66 output=round(op,2)
67

/usr/local/lib/python3.6/dist-packages/skfuzzy/defuzzify/defuzz.py in defuzz(x, mfx, mode)
246 if 'centroid' in mode or 'bisector' in mode:
247 zero_truth_degree = mfx.sum() == 0 # Approximation of total area
--> 248 assert not zero_truth_degree, 'Total area is zero in defuzzification!'
249
250 if 'centroid' in mode:

AssertionError: Total area is zero in defuzzification!

running the same code for dataset Sentiment140 giving above error