// ❌ WRONG: Storing collection's extend_ref
fun init_module(deployer: &signer) {
    let collection_ref = collection::create_unlimited_collection(...);
    let collection_signer = object::generate_signer(&collection_ref);

    move_to(&collection_signer, Config {
        extend_ref: object::generate_extend_ref(&collection_ref),  // Wrong ref!
    });
}

public entry fun mint_nft() acquires Config {
    let config = borrow_global<Config>(...);
    let signer = object::generate_signer_for_extending(&config.extend_ref);

    // ❌ ERROR: Collection can't create tokens in itself
    token::create_named_token(&signer, ...);
}

// ✅ CORRECT: Create marketplace object that OWNS the collection
fun init_module(deployer: &signer) {
    // Create marketplace state object
    let marketplace_ref = object::create_named_object(deployer, b"MARKETPLACE_STATE");
    let marketplace_signer = object::generate_signer(&marketplace_ref);

    // Marketplace creates collection (marketplace is the owner)
    collection::create_unlimited_collection(&marketplace_signer, ...);

    // Store MARKETPLACE object's extend_ref
    move_to(&marketplace_signer, MarketplaceConfig {
        extend_ref: object::generate_extend_ref(&marketplace_ref),
    });
}

public entry fun mint_nft() acquires MarketplaceConfig {
    let config = borrow_global<MarketplaceConfig>(...);

    // Use marketplace signer (collection owner)
    let marketplace_signer = object::generate_signer_for_extending(&config.extend_ref);
    token::create_named_token(&marketplace_signer, ...);  // ✅ Works!
}

// During deployment, init_module failed an assertion
fun init_module(deployer: &signer) {
    assert!(signer::address_of(deployer) == @marketplace_addr, E_NOT_AUTHORIZED);
    // If this fails, MarketplaceConfig is never created
    move_to(deployer, MarketplaceConfig { ... });
}

// ❌ WRONG: Incorrect seed or creator address
let obj_addr = object::create_object_address(&wrong_creator, b"SEED");
let config = borrow_global<Config>(obj_addr);  // Doesn't exist at this address

// ✅ CORRECT: Use correct creator address and seed
let obj_addr = object::create_object_address(&@marketplace_addr, b"MARKETPLACE_STATE");
let config = borrow_global<MarketplaceConfig>(obj_addr);

// ❌ WRONG
public entry fun mint_and_transfer(creator: &signer, recipient: address) {
    let constructor_ref = token::create_named_token(...);
    let transfer_ref = object::generate_transfer_ref(&constructor_ref);

    // Disable ungated transfers
    object::disable_ungated_transfer(&transfer_ref);

    let token_obj = object::object_from_constructor_ref<Token>(&constructor_ref);

    // ❌ ERROR: ungated transfers are disabled!
    object::transfer(creator, token_obj, recipient);
}

// ✅ CORRECT
public entry fun mint_and_transfer(creator: &signer, recipient: address) {
    let constructor_ref = token::create_named_token(...);
    let transfer_ref = object::generate_transfer_ref(&constructor_ref);

    // Disable ungated transfers
    object::disable_ungated_transfer(&transfer_ref);

    // ✅ Use transfer_with_ref instead
    let linear_transfer_ref = object::generate_linear_transfer_ref(&transfer_ref);
    object::transfer_with_ref(linear_transfer_ref, recipient);

    // Store transfer_ref for future transfers
    let token_signer = object::generate_signer(&constructor_ref);
    move_to(&token_signer, TokenData { transfer_ref, ... });
}

// ❌ WRONG: Inconsistent seeds
let obj = object::create_named_object(creator, b"SEED_V1");

// Later, trying to access with different seed
let obj_addr = object::create_object_address(&creator_addr, b"SEED_V2");  // Wrong seed!

// ✅ CORRECT: Use consistent seeds
const SEED: vector<u8> = b"MY_OBJECT_SEED";

// Creation
let obj = object::create_named_object(creator, SEED);

// Access
let obj_addr = object::create_object_address(&creator_addr, SEED);

// ❌ WRONG
let item = borrow_global<Item>(item_obj);  // Passing Object<Item>, need address

// ✅ CORRECT
let item_addr = object::object_address(&item_obj);
let item = borrow_global<Item>(item_addr);

// ❌ WRONG
public fun get_balance(addr: address): u64 {  // Missing 'acquires'
    let account = borrow_global<Account>(addr);
    account.balance
}

// ✅ CORRECT
public fun get_balance(addr: address): u64 acquires Account {
    let account = borrow_global<Account>(addr);
    account.balance
}

// ❌ WRONG
assert!(condition, 0);  // Using 0 - unclear what failed

// ✅ CORRECT
const E_CONDITION_FAILED: u64 = 1;
assert!(condition, E_CONDITION_FAILED);

use std::debug;

public fun my_function(x: u64, y: u64) {
    debug::print(&x);
    debug::print(&y);
    let result = x + y;
    debug::print(&result);
}

// When you see: ABORTED: 0x1 (error code 1)
// Find the constant with value 1:
const E_NOT_OWNER: u64 = 1;  // This is what failed

// Access control: 1-9
const E_NOT_OWNER: u64 = 1;
const E_NOT_ADMIN: u64 = 2;
const E_UNAUTHORIZED: u64 = 3;

// Input validation: 10-19
const E_ZERO_AMOUNT: u64 = 10;
const E_AMOUNT_TOO_HIGH: u64 = 11;
const E_INVALID_ADDRESS: u64 = 12;

// State errors: 20-29
const E_NOT_INITIALIZED: u64 = 20;
const E_ALREADY_INITIALIZED: u64 = 21;
const E_PAUSED: u64 = 22;

// Business logic: 30+
const E_INSUFFICIENT_BALANCE: u64 = 30;