fix(math): FormatInt returns error on empty string (#15714)

math/CHANGELOG.md

@@ -34,6 +34,12 @@ Ref: https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.j
 
 # Changelog
 
+## [Unreleased]
+
+### Bug Fixes
+
+* [#15714](https://github.com/cosmos/cosmos-sdk/pull/15714) `FormatInt` returns an error on empty string
+
 ## [math/v1.0.0](https://github.com/cosmos/cosmos-sdk/releases/tag/math/v1.0.0) - 2023-03-23
 
 ### Bug Fixes

math/int.go

@@ -457,6 +457,10 @@ var stringsBuilderPool = &sync.Pool{
 // string following ADR-050. This function operates with string manipulation
 // (instead of manipulating the int or sdk.Int object).
 func FormatInt(v string) (string, error) {
+	if len(v) == 0 {
+		return "", fmt.Errorf("cannot format empty string")
+	}
+
 	sign := ""
 	if v[0] == '-' {
 		sign = "-"

math/int_test.go

@@ -473,6 +473,11 @@ func TestFormatIntNonDigits(t *testing.T) {
 	}
 }
 
+func TestFormatIntEmptyString(t *testing.T) {
+	_, err := math.FormatInt("")
+	require.ErrorContains(t, err, "cannot format empty string")
+}
+
 func TestFormatIntCorrectness(t *testing.T) {
 	tests := []struct {
 		in   string