feat: Implement Error Handling Module

land_registry/src/errors.cairo

@@ -0,0 +1,13 @@
+/////////////////
+//CUSTOM ERRORS
+/////////////////
+mod Errors {
+    const MINT_NFT: felt252 = 'Only land registry can mint';
+    const TRANSFER_NFT: felt252 = 'Only land registry can transfer';
+    const UPDATE_BY_OWNER: felt252 = 'Only owner can update land';
+    const ONLY_OWNER_TRNF: felt252 = 'Only owner can transfer';
+    const LAND_APPROVAL: felt252 = 'Land must be approved';
+    const NO_LAND: felt252 = 'Land not found';
+    const INSPECTOR_APPROVE: felt252 = 'Only inspector can approve';
+    const INSPECTOR_REJECT: felt252 = 'Only inspector can reject';
+}

land_registry/src/land_nft.cairo

@@ -1,6 +1,7 @@
 use starknet::ContractAddress;
 use openzeppelin::token::erc721::ERC721Component;
 use openzeppelin::introspection::src5::SRC5Component;
+use crate::land_registry::errors::Errors;
 
 #[starknet::interface]
 pub trait ILandNFT<TContractState> {
@@ -17,7 +18,7 @@ pub mod LandNFT {
     use openzeppelin::token::erc721::{ERC721Component, ERC721Component::InternalTrait};
     use openzeppelin::introspection::src5::SRC5Component;
     use openzeppelin::token::erc721::ERC721HooksEmptyImpl;
-
+    use crate::land_registry::errors::Errors;
 
     component!(path: ERC721Component, storage: erc721, event: ERC721Event);
     component!(path: SRC5Component, storage: src5, event: SRC5Event);
@@ -56,10 +57,7 @@ pub mod LandNFT {
     impl LandNFTImpl of ILandNFT<ContractState> {
         fn mint(ref self: ContractState, to: ContractAddress, token_id: u256) {
             // Only the land registry contract can mint NFTs
-            assert(
-                starknet::get_caller_address() == self.land_registry.read(),
-                'Only land registry can mint'
-            );
+            assert(starknet::get_caller_address() == self.land_registry.read(), Errors::MINT_NFT);
             self.erc721.mint(to, token_id);
         }
 
@@ -68,8 +66,7 @@ pub mod LandNFT {
         ) {
             // Only the land registry contract can transfer NFTs
             assert(
-                starknet::get_caller_address() == self.land_registry.read(),
-                'Only land registry can transfer'
+                starknet::get_caller_address() == self.land_registry.read(), Errors::TRANSFER_NFT
             );
             self.erc721.transfer(from, to, token_id);
         }

land_registry/src/land_register.cairo

@@ -6,6 +6,7 @@ pub mod LandRegistryContract {
     use land_registry::utils::utils::{create_land_id, LandUseIntoOptionFelt252};
     use core::array::ArrayTrait;
     use starknet::storage::{Map, StorageMapWriteAccess, StorageMapReadAccess};
+    use crate::land_registry::errors::Errors;
 
 
     #[storage]
@@ -122,7 +123,7 @@ pub mod LandRegistryContract {
         }
 
         fn update_land(ref self: ContractState, land_id: u256, area: u256, land_use: LandUse) {
-            assert(InternalFunctions::only_owner(@self, land_id), 'Only owner can update land');
+            assert(InternalFunctions::only_owner(@self, land_id), Errors::UPDATE_BY_OWNER);
             let mut land = self.lands.read(land_id);
             land.area = area;
             land.land_use = land_use;
@@ -132,8 +133,8 @@ pub mod LandRegistryContract {
         }
 
         fn transfer_land(ref self: ContractState, land_id: u256, new_owner: ContractAddress) {
-            assert(InternalFunctions::only_owner(@self, land_id), 'Only owner can transfer');
-            assert(self.approved_lands.read(land_id), 'Land must be approved');
+            assert(InternalFunctions::only_owner(@self, land_id), Errors::ONLY_OWNER_TRNF);
+            assert(self.approved_lands.read(land_id), Errors::LAND_APPROVAL);
 
             let mut land = self.lands.read(land_id);
             let old_owner = land.owner;
@@ -155,7 +156,7 @@ pub mod LandRegistryContract {
                 i += 1;
             };
 
-            assert(index_to_remove < old_owner_land_count, 'Land not found');
+            assert(index_to_remove < old_owner_land_count, Errors::NO_LAND);
 
             if index_to_remove < old_owner_land_count - 1 {
                 let last_land = self.owner_lands.read((old_owner, old_owner_land_count - 1));
@@ -182,7 +183,7 @@ pub mod LandRegistryContract {
         }
 
         fn approve_land(ref self: ContractState, land_id: u256) {
-            assert(InternalFunctions::only_inspector(@self), 'Only inspector can approve');
+            assert(InternalFunctions::only_inspector(@self), Errors::INSPECTOR_APPROVE);
             self.approved_lands.write(land_id, true);
 
             // Mint NFT
@@ -195,7 +196,7 @@ pub mod LandRegistryContract {
         }
 
         fn reject_land(ref self: ContractState, land_id: u256) {
-            assert(InternalFunctions::only_inspector(@self), 'Only inspector can reject');
+            assert(InternalFunctions::only_inspector(@self), Errors::INSPECTOR_REJECT);
             let mut land = self.lands.read(land_id);
             land.is_approved = false;
             self.lands.write(land_id, land);

land_registry/src/lib.cairo

@@ -2,4 +2,4 @@ pub mod interface;
 pub mod land_register;
 pub mod utils;
 pub mod land_nft;
-
+pub mod errors;