Prevent out of bounds error on title with only whitespace

postrender.go

@@ -182,7 +182,7 @@ func applyMarkdownSpecial(data []byte, skipNoFollow bool, baseURL string, cfg *c
 }
 
 func applyBasicMarkdown(data []byte) string {
-	if len(data) == 0 {
+	if len(bytes.TrimSpace(data)) == 0 {
 		return ""
 	}
 

postrender_test.go

@@ -19,6 +19,12 @@ func TestApplyBasicMarkdown(t *testing.T) {
 		result string
 	}{
 		{"empty", "", ""},
+		{"empty spaces", "  ", ""},
+		{"empty tabs", "\t", ""},
+		{"empty newline", "\n", ""},
+		{"nums", "123", "123"},
+		{"dot", ".", "."},
+		{"dash", "-", "-"},
 		{"plain", "Hello, World!", "Hello, World!"},
 		{"multibyte", "こんにちは", `こんにちは`},
 		{"bold", "**안녕하세요**", `<strong>안녕하세요</strong>`},