tpl: check for too many arguments in apply

Fixes #1091

tpl/template_funcs.go

@@ -668,6 +668,8 @@ func applyFnToThis(fn, this reflect.Value, args ...interface{}) (reflect.Value,
 
 	if len(args) < num {
 		return reflect.ValueOf(nil), errors.New("Too few arguments")
+	} else if len(args) > num {
+		return reflect.ValueOf(nil), errors.New("Too many arguments")
 	}
 
 	res := fn.Call(n)

tpl/template_test.go

@@ -15,7 +15,9 @@ func TestTplGoFuzzReports(t *testing.T) {
 		// Issue #1089
 		{"{{apply .C \"first\" }}", 2},
 		// Issue #1090
-		{"{{ slicestr \"000000\" 10}}", 2}} {
+		{"{{ slicestr \"000000\" 10}}", 2},
+		// Issue #1091
+		{"{{apply .C \"first\" 0 0 0}}", 2}} {
 		templ := New()
 
 		d := &Data{