(Fix) Adapt app to back-end changes (#736)

* refactor: Set success status to `201` (CREATED)

* refactor: return `null` when there's no latestTx

src/logic/safe/transactions/txHistory.js

@@ -63,6 +63,8 @@ export const buildTxServiceUrl = (safeAddress: string) => {
   return `${host}${base}`
 }
 
+const SUCCESS_STATUS = 201 // CREATED status
+
 export const saveTxToHistory = async ({
   baseGas,
   data,
@@ -116,7 +118,7 @@ export const saveTxToHistory = async ({
   )
   const response = await axios.post(url, body)
 
-  if (response.status !== 202) {
+  if (response.status !== SUCCESS_STATUS) {
     return Promise.reject(new Error('Error submitting the transaction'))
   }
 

src/routes/safe/store/actions/utils.js

@@ -8,7 +8,7 @@ export const getLastTx = async (safeAddress: string): Promise<TransactionProps>
     const url = buildTxServiceUrl(safeAddress)
     const response = await axios.get(url, { params: { limit: 1 } })
 
-    return response.data.results[0]
+    return response.data.results[0] || null
   } catch (e) {
     console.error('failed to retrieve last Tx from server', e)
     return null