[v2.0] Object version of `handler` not supported for `_error`, `_500` and `_404`

[csvn]

While migrating a page from Fresh v1 to v2-alpha, I noticed that the handler stopped working for what was previously _404 in the new _error.

The issue seems to stem from using the objectMethod type of handler over just a function for GET:

export const handler = define.handlers({
  GET(ctx) {
    // Return 404 with no HTML body if URL looks to be file-like
    const is404 = ctx.error instanceof HttpError && ctx.error.status === 404;
    const isFileLike = fileExtensions.some((ext) => ctx.url.pathname.endsWith(ext));

    if (is404  && isFileLike) return new Response('', { status: 404, statusText: 'Not found' });

    return page();
  }
});

// When changed to the below style it started working:
export const handler = define.handlers((ctx) => {
  // Same method body
});

There are two "FIXME"'s in the code that is most likely the cause of this issue:

• https://github.com/denoland/fresh/blob/main/src/plugins/fs_routes/mod.ts#L252
• https://github.com/denoland/fresh/blob/main/src/plugins/fs_routes/mod.ts#L279

Solution

A quick fix would be to log a warning until the issue is fixed.

• Should _404 support any other handler types than GET?
• Does _500/_error support methods other than GET?