fix(provider): allow the user to handle the contract errors

src/contract/default.ts

@@ -17,6 +17,7 @@ import {
   Overrides,
   ParsedStruct,
   Result,
+  ResultAccessor,
   StructAbi,
 } from '../types';
 import { BigNumberish, toBN, toFelt } from '../utils/number';
@@ -523,7 +524,10 @@ export class Contract implements ContractInterface {
    * @param response  - response from the method
    * @return - parsed response corresponding to the abi
    */
-  protected parseResponse(method: string, response: string[]): Result {
+  protected parseResponse(method: string, response?: string[]): Result {
+    if (!response) {
+      return undefined;
+    }
     const { outputs } = this.abi.find((abi) => abi.name === method) as FunctionAbi;
     const responseIterator = response.flat()[Symbol.iterator]();
     const resultObject = outputs.flat().reduce((acc, output) => {
@@ -537,7 +541,7 @@ export class Contract implements ContractInterface {
       acc.push(value);
       acc[key] = value;
       return acc;
-    }, [] as Result);
+    }, [] as ResultAccessor);
   }
 
   public invoke(

src/provider/default.ts

@@ -25,7 +25,7 @@ import { parse, stringify } from '../utils/json';
 import { BigNumberish, bigNumberishArrayToDecimalStringArray, toBN, toHex } from '../utils/number';
 import { compressProgram, randomAddress } from '../utils/stark';
 import { ProviderInterface } from './interface';
-import { BlockIdentifier, getFormattedBlockIdentifier } from './utils';
+import { BlockIdentifier, GatewayError, getFormattedBlockIdentifier } from './utils';
 
 type NetworkName = 'mainnet-alpha' | 'goerli-alpha';
 
@@ -159,9 +159,11 @@ export class Provider implements ProviderInterface {
       body: stringify(request),
       headers,
     })
-      .then((res) => {
+      .then(async (res) => {
         if (res.status >= 400) {
-          throw Error(res.statusText);
+          // This will allow user to handle contract errors
+          const responseBody = parse(await res.text());
+          throw new GatewayError(responseBody.message, responseBody.code);
         }
         return res.text();
       })

src/provider/utils.ts

@@ -82,3 +82,9 @@ export function getFormattedBlockIdentifier(blockIdentifier: BlockIdentifier = n
   }
   return `blockHash=${toHex(toBN(blockIdentifierObject.data))}`;
 }
+
+export class GatewayError extends Error {
+  constructor(message: string, public errorCode: string) {
+    super(message);
+  }
+}

src/types/contract.ts

@@ -1,5 +1,6 @@
 export type AsyncContractFunction<T = any> = (...args: Array<any>) => Promise<T>;
 export type ContractFunction = (...args: Array<any>) => any;
-export interface Result extends Array<any> {
+export interface ResultAccessor extends Array<any> {
   [key: string]: any;
 }
+export type Result = ResultAccessor | undefined;