Hotfix/validating query result length (#3053)

* Validating that there are txs in the query results before loop throught the array

* Created tests to validate the error has been fixed

* Added comments

* Fixing misspeling

* check if the variable "skipCount" is bigger than zero. If it is not, we set it to 0. If it, we do not do anything.

* using function that validates the skipCount variable

* undo Gopkg.lock changes

rpc/core/pipe.go

@@ -154,3 +154,12 @@ func validatePerPage(perPage int) int {
 	}
 	return perPage
 }
+
+func validateSkipCount(page, perPage int) int {
+	skipCount := (page - 1) * perPage
+	if skipCount < 0 {
+		return 0
+	}
+
+	return skipCount
+}

rpc/core/tx.go

@@ -201,10 +201,11 @@ func TxSearch(query string, prove bool, page, perPage int) (*ctypes.ResultTxSear
 	totalCount := len(results)
 	perPage = validatePerPage(perPage)
 	page = validatePage(page, perPage, totalCount)
-	skipCount := (page - 1) * perPage
+	skipCount := validateSkipCount(page, perPage)
 
 	apiResults := make([]*ctypes.ResultTx, cmn.MinInt(perPage, totalCount-skipCount))
 	var proof types.TxProof
+	// if there's no tx in the results array, we don't need to loop through the apiResults array
 	for i := 0; i < len(apiResults); i++ {
 		r := results[skipCount+i]
 		height := r.Height