REVERT opcode executed. Message: SafeMath: subtraction overflow - blockchain

Question

When I trigger buyMembership function from shasta.tronscan.io I am getting this error.
library SafeMath was working fine lately. But I do not know why it is giving me this error.
Please help me sort this thing I have already wasted a complete day on this.
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
This is ITRC20 interface
interface ITRC20 {
function totalSupply() external view returns (uint256);
function balanceOf(address account) external view returns (uint256);
function transfer(address recipient, uint256 amount) external returns (bool);
function allowance(address owner, address spender) external view returns (uint256);
function approve(address spender, uint256 amount) external returns (bool);
function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
event Transfer(address indexed from, address indexed to, uint256 value);
event Approval(address indexed owner, address indexed spender, uint256 value);
}
SafeMath library I used.
library SafeMath {
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, "SafeMath: addition overflow");
return c;
}
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
require(b <= a, "SafeMath: subtraction overflow");
uint256 c = a - b;
return c;
}
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b, "SafeMath: multiplication overflow");
return c;
}
function div(uint256 a, uint256 b) internal pure returns (uint256) {
require(b > 0, "SafeMath: division by zero");
uint256 c = a / b;
return c;
}
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
require(b != 0, "SafeMath: modulo by zero");
return a % b;
}
}
This is my contract. buyMembership function with correct params generates this error of
REVERT opcode executed. Message: SafeMath: subtraction overflow
contract TEST101 {
ITRC20 USDT;
address payable public owner;
address payable public ma;
address payable public fw;
struct User {
uint256 commission_balance;
uint256 member_id;
uint40 membership_time;
uint256 order_history;
}
struct History {
uint256 order_amount;
uint40 order_time;
}
struct Admin {
uint256 active;
}
mapping(uint256 => User) public users;
mapping(address => Admin) public admins;
mapping(uint256 => mapping(uint256 => History)) public histories;
event BuymemberShip(address user_wallet, uint256 member_id, uint256 amount, uint40 time);
event BuyProduct(address user_wallet, uint256 member_id, uint256 amount, uint40 time);
event Withdraw(address user_wallet, uint256 member_id, uint256 amount, uint40 time);
event UpdateBalance(address user_wallet, uint256 member_id, uint256 amount, uint40 time);
constructor(address payable _ma, ITRC20 _usdt, address payable _fw) {
ma = _ma;
owner = payable(msg.sender);
USDT = _usdt;
fw = _fw;
}
function buyMembership(uint256 _mid, uint256 _amount, uint256 _charges) external {
USDT.transferFrom(msg.sender, address(this), _amount);
users[_mid].membership_time = uint40(block.timestamp);
users[_mid].order_history = 0;
users[_mid].member_id = _mid;
USDT.transfer(fw, _charges);
emit BuymemberShip(msg.sender, _mid, _amount, uint40(block.timestamp));
}
function purchase(uint256 _mid, uint256 _amount) external {
USDT.transferFrom(msg.sender, address(this), _amount);
users[_mid].order_history += 1;
histories[_mid][users[_mid].order_history].order_amount = _amount;
histories[_mid][users[_mid].order_history].order_time = uint40(block.timestamp);
emit BuyProduct(msg.sender, _mid, _amount, uint40(block.timestamp));
}
function withdraw(address addr, uint256 _mid, uint256 _amount) external {
if (admins[msg.sender].active == 1 || msg.sender == ma) {
if (users[_mid].commission_balance >= _amount) {
users[_mid].commission_balance -= _amount;
USDT.transfer(msg.sender, _amount);
emit Withdraw(msg.sender, _mid, _amount, uint40(block.timestamp));
} else {
revert("not enough balance");
}
} else {
revert("permission denied");
}
}
}