Question: Repeating command generates error

> restart; with(VectorCalculus);
> P := proc (rho, theta, phi) options operator, arrow; `<,>`(rho*cos(phi)*sin(theta), rho*sin(phi)*sin(theta), rho*cos(theta)) end proc;
> r[1] := proc (t) options operator, arrow; P(2, (1/2)*Pi, t) end proc;
> F := VectorField(`<,>`(x, VectorCalculus[`+`](y, R), z), coords = cartesian[x, y, z]);
> F[1] := evalVF(F, r[1](t));
                Vector[column](%id = 255051836)
> F[1] := evalVF(F, r[1](t));
Error, invalid input: VectorCalculus:-evalVF expects its 1st argument, F, to be of type {procedure, Vector(algebraic)}, but received Vector(3, {(1) = Vector(3, {(1) = 2*cos(t), (2) = 2*sin(t)+R, (3) = 0}, attributes = [space = (module () local _origin, _coords, _coords_dim; export GetCoordinates, GetRootPoint, Vector; end module)]), (2) = y+R, (3) = z}, attributes = [vectorfield, coords = cartesian[x, y, z]])
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