Assert types instead of casting in Express

[goodoldneon]

Description

• In the Express serve function, assert types instead of casting.
• When parsing function data, include Zod validation errors in the pretty error.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: d53df54d92f8bd69b9df9d83d937424d5a31f56d

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

| Name | Type | | ------- | ----- | | inngest | Patch |

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Click here if you're a maintainer who wants to add another changeset to this PR

[jpwilliams]

After looking at this, we have some errors for occurrences like a signing key being missing where we'd like the handler to fall back to those high-quality errors; a handler should probably only attempt to retrieve values and not be the one that understands how to error.

I'm going to shift this to add some context to the error when failing to parse and leave the casting for now.

[inngest-release-bot]

The backport to v1.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-v1.x v1.x
# Navigate to the new working tree
cd .worktrees/backport-v1.x
# Create a new branch
git switch --create backport-272-to-v1.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 acfa07c3da400e9e27650bd59eb33ad0ecc69451
# Push it to GitHub
git push --set-upstream origin backport-272-to-v1.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-v1.x

Then, create a pull request where the base branch is v1.x and the compare/head branch is backport-272-to-v1.x.