feat: set default rpc endpoint (#485)

* feat: add default RPC endpoint

* feat: removed setting RPC endpoint altogherher and altered the routes accordingly

src/providers/TopUp.tsx

@@ -1,5 +1,6 @@
 import { providers, Wallet } from 'ethers'
 import { createContext, ReactElement, useEffect, useState } from 'react'
+import config from '../config'
 import { setJsonRpcInDesktop } from '../utils/desktop'
 
 const LocalStorageKeys = {
@@ -10,18 +11,18 @@ const LocalStorageKeys = {
 }
 
 interface ContextInterface {
-  providerUrl: string | null
-  provider: providers.JsonRpcProvider | null
+  providerUrl: string
+  provider: providers.JsonRpcProvider
   giftWallets: Wallet[]
   setProviderUrl: (providerUrl: string) => void
   addGiftWallet: (wallet: Wallet) => void
 }
 
-const providerUrl = localStorage.getItem('json-rpc-provider') || null
+const providerUrl = localStorage.getItem('json-rpc-provider') || config.DEFAULT_RPC_URL
 
 const initialValues: ContextInterface = {
   providerUrl,
-  provider: providerUrl ? new providers.JsonRpcProvider(providerUrl) : null,
+  provider: new providers.JsonRpcProvider(providerUrl),
   giftWallets: [],
   setProviderUrl: () => {}, // eslint-disable-line
   addGiftWallet: () => {}, // eslint-disable-line