Invalid Constraints error in Non-linear Optimization

I am trying to write the code to solve a certain optimal control problem, but I keep running into an issue when I pass on my constraints to NMininimize[]. The following is my code:

(*PROBLEM DEFINITION*)
(*Inputs*)
t0 = 0;     (*Start Time*)
tf = 1;     (*End Time*)
time = {t0, tf};

nx = 2;     (*Number of States*)
nu = 1;     (*Number of Inputs*)

(*Initial conditions for system. Bounds if x0 is free s.t. x0l=< x0 <=x0u
If fixed, x0l == x0u*)
x0l = {0, 1};
x0u = {0, 1};

(*State bounds. xl=< x <=xu*)
limit = 1;
xl = {-Infinity, -Infinity};
xu = {limit, Infinity};

(*Terminal state bounds. xfl=< xf <=xfu. If fixed: xfl == xfu*)
xfl = {0, -1};
xfu = {0, -1};

(*Input Bounds*)
ul = -Infinity;
uu = Infinity;

(*Bounds on the first control action*)
u0l = -Infinity;
u0u = Infinity;

(*Define problem structures*)
states = <|"x0l" -> x0l, "x0u" -> x0u, "xl" -> xl, "xu" -> xu, "xfl" -> xfl,
 "xfu" -> xfu, "ul" -> ul, "uu" -> uu, "u0l" -> u0l, "u0u" -> u0u|>;
 
problem = <|"time" -> time, "nx" -> nx, "nu" -> nu, "states" -> states|>;

(*Define system dynamics*)
fx1[x_, u_, t_] := x[[2]];
fx2[x_, u_, t_] := u;
dynamics[x_, u_, t_] := {fx1[x, u, t], fx2[x, u, t]};

(*Define cost functions*)
lag[x_, u_, t_] := 0.5*(u^2); (*Define lagrangian cost*)
terminalCost[x_, u_, t_] := 0;             (*Terminal cost*)

nsteps = 10;
h = (tf - t0)/nsteps;
d = 5;
tau = Subdivide[t0, tf, nsteps]

(*Threshold*)
thresh = 1e-4

(*Problem related constants*)
Symbol["x"]
Symbol["beta"]

xarr = Array[x, {nx, Length[tau]}]
betaarr = Array[beta, Length[tau]]

(*Define basis vector and approximation function*)
phi[t_, taui_, h_, d_] := 1/Sqrt[Pi*d]*Exp[-(t-taui)^2/(D*h^2)];

Mhdx[t_, tau_, x_, h, d] := Dot[x, phi[t, tau, h, d]];

uhat[t_] := Mhdx[t, tau, betaarr, h, d];

uapp = {};
For[i = 1, i <= (nsteps + 1), i++, AppendTo[uapp, uhat[tau[[i]]]]];
uapp;
(*Calculating cost expressions*)
J = 0;
For[i = 1, i < nsteps+1, i++, J = J + lag[xarr[[;;, i]], uapp[[i]], tau[[i]]]*h];
J = J + terminalCost[xarr[[;;, -1]], uapp[[-1]], tau[[-1]]];

(*Constraints*)
xnextlist = {};
For[k = 1, k <nsteps+1, k++, 
xnext = xarr[[;;, k]] + dynamics[xarr[[;;, k]], uapp[[k]], tau[[k]]]*h;
AppendTo[xnextlist, xnext]];
xnextlist = Transpose[xnextlist];

xnextlist;
errlist = Abs[xnextlist - xarr[[;;, 2;;-1]]]
checkdynamicconstraints[err_] := AllTrue[err, # <= thresh &] (*Check is constraints based on dynamics satisfied*)

checkinitstateconstraints[x_] := x[[1, 1]] >= x0l[[1]] && x[[1, 1]] <= x0u[[1]] && x[[2, 1]] >= x0l[[2]] && x[[2, 1]] <= x0u[[2]];
checkfinalstateconstraints[x_] := x[[1, -1]] >= xfl[[1]] && x[[1, -1]] <= xfu[[1]] && x[[2, -1]] >= xfl[[2]] && x[[2, -1]] <= xfu[[2]]; 
checkstateconstraints[x_] := AllTrue[x[[1, 2;;-2]], (# >= xl[[1]] && # <= xu[[1]])&] && AllTrue[x[[2, 2;;-2]], (# >= xl[[2]] && # <= xu[[2]])&];

checkinitcontrolconstraints[u_] := u[[1]] >= u0l && u[[1]] <= u0u;
checkcontrolconstraints[u_] := AllTrue[u[[2;;-1]], # >= ul &] && AllTrue[u[[2;;-1]], # <= uu &];

solution = NMinimize[{J, checkcontrolconstraints[uapp], checkdynamicconstraints[errlist], checkfinalstateconstraints[xarr], checkinitcontrolconstraints[uapp], checkinitstateconstraints[xarr]}, Join[betaarr, xarr[[1]], xarr[[2]]]];

I'm facing the following error when I try to run this code:

NMinimize::bcons: The following constraints are not valid: {x[1,1]>=0,x[1,11]>=0,x[2,1]>=1,x[2,11]>=-1,Abs[x[1,1]-x[1,2]+1/10 x[2,1]]<=-4+e,<<18>>,Abs[1/10 (Power[<<2>>] Power[<<2>>] beta[<<1>>]+Power[<<2>>] Power[<<2>>] beta[<<1>>]+Power[<<2>>] Power[<<2>>] beta[<<1>>]+Power[<<2>>] Power[<<2>>] beta[<<1>>]+Power[<<2>>] Power[<<2>>] beta[<<1>>]+Power[<<2>>] Power[<<2>>] beta[<<1>>]+Power[<<2>>] Power[<<2>>] beta[<<1>>]+Power[<<2>>] Power[<<2>>] beta[<<1>>]+Power[<<2>>] Power[<<2>>] beta[<<1>>]+Power[<<2>>] beta[<<1>>]+Power[<<2>>] Power[<<2>>] beta[<<1>>])+x[2,10]-x[2,11]]<=-4+e,x[1,1]<=0,x[1,11]<=0,x[2,1]<=1,x[2,11]<=-1}. Constraints should be equalities, inequalities, or domain specifications involving the variables.

I can see that all the constraints being passed on to NMinimize[] are inequalities, but I keep getting this error saying they aren't. How do I resolve this?

PS. This is my first time posting on StackExchange so forgive me for bad formatting.