Handle division by zero

src/builtins.c

@@ -121,6 +121,7 @@ LISP_FUNC_2(ucl_builtin_div, state, arg0, arg1) {
         return ucl_error_create("Invalid type of argument 1 to 'div'");
     }
 
+    UCL_COND_OR_RET_ERROR(arg1->integer != 0, "Division by zero");
     return ucl_int_create(arg0->integer / arg1->integer);
 }