Accessing a coupled array's du_dot_du

[NateAM]

Discussed in #25832

^{Originally posted by NateAM October 24, 2023}
I'm having some trouble accessing a coupled array's _du_dot_du variable. In my header I define

myClass.h

...
const VariableValue & _dv_dot_dv;
...

and in the source file I define

myClass.C

InputParameters myClass::validParams( ){
    ...
    params.addRequiredCoupledVariable( "v", "my docstring" );
    ...
}

myClass::myClass( const InputParameters & parameters )
    : myBaseClass( parameters ),
    ...
    _v( coupledArrayValue( "v" ) ),
    _v_dot( coupledArrayDot( "v" ) ),
    _dv_dot_dv( coupledDotDu( "v" ) ),
    ...{
}

When I run this, I get the moose error:

*** ERROR ***
Variable 'v' is of a different C++ type than you tried to fetch it as.

I will work to implement coupledArrayDotDu into Coupleable.