In the upcoming lecture, we will be adding a catch block to our src/routes/cells.ts file. Similar to a lecture earlier in this section, we will need to add a type guard and type predicate. 

To resolve, make the following changes:

1) Add an additional interface:

interface LocalApiError {
  code: string;
}

2) Add a function to return the predicate:

...

  router.get("/cells", async (req, res) => {
    const isLocalApiError = (err: any): err is LocalApiError => {
      return typeof err.code === "string";
    };

...

3) Update the catch block to use the type guard:

...

    } catch (err) {
      if (isLocalApiError(err)) {
        if (err.code === "ENOENT") {
          await fs.writeFile(fullPath, "[]", "utf-8");
          res.send([]);
        }
      } else {
        throw err;
      }
    }
  });

...