error message threw error message

`sys` had gone away from the function body, so it had to be grabbed from elsewhere

Author: baggepinnen

src/linearization.jl

@@ -349,7 +349,7 @@ function CommonSolve.solve(prob::LinearizationProblem; allow_input_derivatives =
         if !iszero(Bs)
             if !allow_input_derivatives
                 der_inds = findall(vec(any(!=(0), Bs, dims = 1)))
-                error("Input derivatives appeared in expressions (-g_z\\g_u != 0), the following inputs appeared differentiated: $(inputs(sys)[der_inds]). Call `linearize` with keyword argument `allow_input_derivatives = true` to allow this and have the returned `B` matrix be of double width ($(2nu)), where the last $nu inputs are the derivatives of the first $nu inputs.")
+                error("Input derivatives appeared in expressions (-g_z\\g_u != 0), the following inputs appeared differentiated: $(inputs(prob.f.prob.f.sys)[der_inds]). Call `linearize` with keyword argument `allow_input_derivatives = true` to allow this and have the returned `B` matrix be of double width ($(2nu)), where the last $nu inputs are the derivatives of the first $nu inputs.")
             end
             B = [B [zeros(nx, nu); Bs]]
             D = [D zeros(ny, nu)]