Final answer:
The 'TypeError: unsupported operand type(s) for NoneType and float' error occurs in Python when trying to perform an arithmetic operation between a None type and a floating-point number. It requires the variable be checked and assigned a numeric value before the operation.
Step-by-step explanation:
The TypeError: unsupported operand type(s) for NoneType and float indicates that an operation was attempted between a NoneType value and a value of type float. In Python, NoneType is the type for the None object, which represents the absence of a value. This error typically occurs when a variable expected to have a numeric value is instead None, making an arithmetic operation like addition or subtraction impossible.
For example, if you have a piece of code like this:
result = some_var + 3.14
If some_var happens to be None, the addition operation would raise the TypeError mentioned. To resolve this error, one would need to ensure that the variable (some_var in this case) is assigned a numerical value (int or float) before the operation, or check its value and handle the case where it might be None.