Hey Friends!
Here’s what’s inside:
The most common mistakes AI generated code leaves behind
Why newer developers get hit hardest
How a human who actually understands the code would have caught each one
Real prevention patterns you can use today
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I have been there.
Extra files nobody cleaned up. Hardcoded API URLs that made my life miserable the moment I reviewed the files. API calls living directly inside components that I had to hunt down and update in four different places when one endpoint changed.
All of it was generated quickly, all of it looked fine, all of it cost me time later.
That is the real danger with vibe coding. The code is not obviously wrong. It runs. It passes your quick test. It ships. And then three weeks later in production, a real user does something unexpected and everything unravels.
Newer developers get hit hardest because you do not yet have the pattern recognition to spot what is off. You trust the output because it works. But working and correct are not the same thing.
Here are the most common time bombs and how a human who actually understands the code would prevent each one.
1. No Error Handling
AI writes for the happy path. Every single time.
No try/catch, no failed state, no consideration for what happens when the network is slow, the API is down, or the data comes back in a shape you did not expect. It assumes everything works because in development, everything usually does.
// Vibe coded
const data = await fetchUser(id)
return data.profile
// Human reviewed
try {
const data = await fetchUser(id)
if (!data?.profile) throw new Error('Profile missing')
return data.profile
} catch (error) {
logger.error(error)
return null
}
The rule is simple: if it touches a network, a database, or user input, it needs error handling. No exceptions. Real users will find every failure state you did not account for, usually at the worst possible time.
2. N+1 Queries
AI does not think about database performance. It thinks about making the logic work. Those are very different goals.
php
// Vibe coded - hits the database once per post
$posts = Post::all();
foreach ($posts as $post) {
echo $post->author->name; // separate query every single iteration
}
// Human reviewed - one query total
$posts = Post::with('author')->get();
foreach ($posts as $post) {
echo $post->author->name;
}
Your app works fine with 10 records in development. It crawls with 10,000 in production. And by the time you notice, the damage is already done.
Any time you are looping over database results and accessing a relationship, ask yourself if you are loading that relationship upfront. In Laravel that is eager loading with with(). In Prisma it is include. The fix is one word. The performance difference is enormous.
3. Hardcoded Values
API keys, URLs, magic numbers baked directly into the code. Works perfectly on your machine. Breaks in staging. Becomes a security issue in production. And when you need to change it, you are searching through your entire codebase hoping you did not miss one.
javascript
// Vibe coded
const response = await fetch('https://api.myservice.com/v1/users')
// Human reviewed
const response = await fetch(`${process.env.NEXT_PUBLIC_API_URL}/users`)
The rule: if it could ever be different between local, staging, and production, it belongs in an environment variable. API URLs, keys, feature flags, timeouts. Anything configurable lives in .env. This is not optional; it is just how production code works.
4. Dead Files and Orphaned Code
AI generates what you asked for, but never cleans up what it replaced. You end up with a project that works, but nobody knows what is safe to delete. Every developer who touches it later wastes hours figuring out what actually matters.
I have opened my own projects and found components that were imported nowhere, utility files that were never called, and entire pages that were replaced but never removed.
Prevention is a quick habit before you ship:
Does every file in this change get imported somewhere?
Use your editor’s find references on components and utilities before assuming they are needed
If you cannot trace a file back to a user action or a route, it probably should not exist
Dead code is not harmless. It is confusion waiting to happen.
5. API Calls Directly in Components
This one starts small and compounds fast.
One fetch inside one component feels fine. Then you need that same data somewhere else so you copy it. Then a third place. Now the endpoint changes and you are updating four files and hoping you did not miss one.
javascript
// Vibe coded - business logic inside UI
function UserProfile({ id }) {
const [user, setUser] = useState(null)
useEffect(() => {
fetch(`https://api.myservice.com/users/${id}`)
.then(r => r.json())
.then(setUser)
}, [id])
return
{user?.name}
}
// Human reviewed - API call lives in its own layer
// lib/api/users.js
export async function getUser(id) {
const res = await fetch(`${process.env.NEXT_PUBLIC_API_URL}/users/${id}`)
if (!res.ok) throw new Error('Failed to fetch user')
return res.json()
}
// components/UserProfile.jsx
function UserProfile({ id }) {
const [user, setUser] = useState(null)
useEffect(() => {
getUser(id).then(setUser).catch(console.error)
}, [id])
return
{user?.name}
}
Now if the endpoint changes, you change it in one place. If you need that data somewhere else, the function already exists. This is separation of concerns and it is one of the most practical architectural habits you can build early.
6. Missing Validation
AI trusts input completely. It takes what comes in, processes it, stores it. No sanitization, no type checking, no length limits.
Validation lives at two layers and you need both:
Frontend for user experience:
javascript
if (!email.includes('@')) return setError('Invalid email')
if (password.length < 8) return setError('Password too short')
Backend for actual security:
php
$validated = $request->validate([
'email' => 'required|email|max:255',
'password' => 'required|min:8',
]);
Frontend validation gives users immediate feedback. Backend validation is what actually protects your app. AI almost never generates either one by default. A human who has seen what real users submit does not skip this.
The Underlying Difference
Vibe coded code asks: does this work?
Human reviewed code asks: what happens when this breaks?
That one mindset shift is the difference between code that runs in development and code that holds up in production. AI is a powerful tool. But it does not know your production environment, your real users, or the consequences of getting it wrong.
You do. That is the part that cannot be automated.
now go ship something great
Building something that needs to actually hold up in production? That is exactly what we do at FabBuilds.
Let’s Build It Beautifully,
Fab