fix out of range error

2 files changed, 9 insertions, 4 deletions

diff --git a/pkg/commands/patch/patch_modifier.go b/pkg/commands/patch/patch_modifier.go
index c2bbc60f6..e5c6d061f 100644
--- a/pkg/commands/patch/patch_modifier.go
+++ b/pkg/commands/patch/patch_modifier.go
@@ -137,12 +137,17 @@ func ModifiedPatchForLines(log *logrus.Entry, filename string, diffText string,
 }
 
 // I want to know, given a hunk, what line a given index is on
-func (hunk *PatchHunk) LineNumberOfLine(idx int) int {
-	lines := hunk.bodyLines[0 : idx-hunk.FirstLineIdx-1]
+func (hunk *PatchHunk) LineNumberOfLine(idx int) (int, error) {
+	n := idx - hunk.FirstLineIdx - 1
+	if n < 0 || len(hunk.bodyLines) <= n {
+		return -1, fmt.Errorf("line index out of range")
+	}
+
+	lines := hunk.bodyLines[0:n]
 
 	offset := nLinesWithPrefix(lines, []string{"+", " "})
 
-	return hunk.newStart + offset
+	return hunk.newStart + offset, nil
 }
 
 func nLinesWithPrefix(lines []string, chars []string) int {
diff --git a/pkg/commands/patch/patch_modifier_test.go b/pkg/commands/patch/patch_modifier_test.go
index 8b866019b..1f1eeb114 100644
--- a/pkg/commands/patch/patch_modifier_test.go
+++ b/pkg/commands/patch/patch_modifier_test.go
@@ -539,7 +539,7 @@ func TestLineNumberOfLine(t *testing.T) {
 
 	for _, s := range scenarios {
 		t.Run(s.testName, func(t *testing.T) {
-			result := s.hunk.LineNumberOfLine(s.idx)
+			result, _ := s.hunk.LineNumberOfLine(s.idx)
 			if !assert.Equal(t, s.expected, result) {
 				fmt.Println(result)
 			}