Fix error handling in strftime

src/builtin.c

@@ -1532,6 +1532,10 @@ static jv f_localtime(jq_state *jq, jv a) {
 static jv f_strftime(jq_state *jq, jv a, jv b) {
   if (jv_get_kind(a) == JV_KIND_NUMBER) {
     a = f_gmtime(jq, a);
+    if (!jv_is_valid(a)) {
+      jv_free(b);
+      return a;
+    }
   } else if (jv_get_kind(a) != JV_KIND_ARRAY) {
     return ret_error2(a, b, jv_string("strftime/1 requires parsed datetime inputs"));
   } else if (jv_get_kind(b) != JV_KIND_STRING) {