Column Cannot Be Null Error in Laravel - Fix

Post::create([
    'title' => $request->title,
    'body' => $request->body,
    'user_id' => auth()->id(),
]);

Schema::table('posts', function (Blueprint $table) {
    $table->string('subtitle')->nullable();
});

$request->validate([
    'title' => 'required|string|max:255',
    'body' => 'required|string',
]);

$table->string('status')->default('draft');