BUG: KeyError: 'I_11' and AttributeError: 'NoneType' object has no attribute 'reset'

[Gui-FernandesBR]

Describe the bug

There's a problem on the Motor.I_11 method. The sum propellant_I_11 + dry_I_11 is returning None for a strange reason. The order of the operations create a non sense result:

        dry_I_11 += (
            self.dry_mass
            * (self.center_of_dry_mass_position - self.center_of_mass) ** 2
        )

This could be translated into:

        np.array +=(
            float 
            * (float - Function) **2
        )

To Reproduce

I have a code example with me but I'll still ask if I can share it. But try to create a liquid motor and then access its I_11 property, is it a function?

Expected behavior

Code should run without problems.

Actually, the #488 solves this problem. I've also tested to invert the operations. I think we can wait for the next release (2~3 weeks) to solve this.

Screenshots

Additional context

Issue firstly reported on discord by Django [DARE].

The error seems to be present since version v1.0.0

[Gui-FernandesBR]

The number 488 already solved this one.
A few weeks from now it should be available at master branch, but the problem is solved tho.