Error in converting symbolic value to numerical value with subs()

I have a problem in MATLAB. I want to calculate the nonlinear system of equation using Newton Method. This nonlinear system of equation is taken from finite difference method. The system is Ay=F(y) where $A$ is a $n-1$ by $n-1$ matrix, y is variable of solution y2, y3, ... yn, and F(y) is a function of y2, y3, ... yn. I try to make the MATLAB code as follows.

clear all;
clc;
fprintf('FINITE DIFFERENCE METHOD FOR NONLINEAR BVP ODE\n\n');
xa=0;
xb=2*pi;
N=50;
h=(xb-xa)/N;
x=xa:h:xb;
n=length(x);
% Matrix A
A=zeros(n-1,n-1);
A(1,1)=-2;
A(1,2)=1;
A(n-1,n-2)=2;
A(n-1,n-1)=-2;
for i=2:n-2
    A(i,i-1)=1;
    A(i,i)=-2;
    A(i,i+1)=1;
end
%symbolic variable [y1;y2,...;yn]
y=sym('y',[n,1]);
%F
F=sym(zeros(n-1,1));
F(n-1)=h^2*sin(2*(x(n)))-h^2*sin(x(n))-h*y(n)*(2*h-2*h*y(n))-2*h+2*h*y(n);
for i=1:n-2
    F(i)=h^2*sin(2*(x(i+1)))-h^2*sin(x(i+1))-h*y(i+1)*(y(i+2)-y(i));
end
%Non Linear System of Equation
G=A*y(2:n)-F;

%Newton Method
X0=zeros(n-1,1);% Initial Value for Newton Method
J=jacobian(G,y(2:n));
galat=1;
eps=1e-10;
k=1;
while galat>eps
    JX0=double(subs(J,y(2:n),X0));
    GX0=double(subs(G,y(2:n),X0));
    X1=X0-JX0\GX0;
    galat=norm(X1-X0);
    X0=X1;
    k=k+1;
end
ynum(1)=0;
ynum(2:n)=X1;%Solution for Newton Method

fprintf('  i     xi        yi          yexc_i         error\n');
for i=1:n 
    yeks(i)=sin(x(i));
    error(i)=abs(ynum(i)-yeks(i));
    fprintf('%3d  %5.2f  %8.10f  %8.10f  %10.10f\n',i,x(i),ynum(i),yeks(i),error(i));
end
subplot(2,1,1);
plot(x,ynum,'>','linewidth',1,'color','r','markerfacecolor','c');
hold on;
plot(x,yeks,'linewidth',1,'color','k');
hold on;
title(sprintf('Numerical solution and Exact Solution for h=%5.3f',h));
xlabel('x');
ylabel('y');
legend('y numerical','y exact');
grid on;
subplot(2,1,2);
plot(x,error,'-','color','r');
grid on;
title('Error');
xlabel('x');
ylabel('y');

But if I run the code, I have following error message:

Error using mupadengine/evalin2double
Unable to convert expression containing symbolic variables into double array. Apply 'subs' function first to substitute values for
variables.

Error in mupadengine/feval2double

Error in sym/double (line 756)
                X = feval2double(symengine, "symobj::doubleDirect", S);
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error in BHPPDNLND (line 38)
    JX0=double(subs(J,y(2:n),X0));
        ^^^^^^^^^^^^^^^^^^^^^^^^^

Anyone know how to solve this problem? The code which have an error, the purpose is substituting the point X0 to jacobian matrix, so I have JX0 on the symbolic value form. I just want to convert the symbolic value to numerical value using double(), but the error message appear. Why this is can happen? Any help will be appreciated.