Fix missing bounds check in errorf verb matching (fixes #29)

Author: polyfloyd

errorlint/printf.go

@@ -14,6 +14,9 @@ func verbOrder(verbs []verb, numArgs int) [][]verb {
 		if v.index != -1 {
 			i = v.index - 1
 		}
+		if i >= len(orderedVerbs) {
+			continue
+		}
 		orderedVerbs[i] = append(orderedVerbs[i], v)
 		verbs = verbs[1:]
 		i++

errorlint/testdata/src/issues/github-29.go

@@ -0,0 +1,8 @@
+package issues
+
+import "fmt"
+
+func Issue29() {
+	err := fmt.Errorf("%v %#[2]v", struct{ string }{})
+	fmt.Println(err)
+}