Univariate Code Incomplete

[windowshopr]

Two issues with your code. First one has the error:

ValueError: view limit minimum -36875.200000000004 is less than 1 and is an invalid Matplotlib date value. This often happens if you pass a non-datetime value to an axis that has datetime units

And the second one is:

Traceback (most recent call last):
  File "Univariate.py", line ..., in <module>
    valid['Predictions'] = closing_price
NameError: name 'closing_price' is not defined

[Nilsonmichiles]

Traceback (most recent call last):
File "Univariate.py", line ..., in
valid['Predictions'] = closing_price
NameError: name 'closing_price' is not defined

How to solve?