Data Not Saving to Supabase Database

1. Missing error handling on insert/update (no .then/.catch)
2. RLS policy blocks INSERT for the user's role
3. Required fields missing or null in submitted data
4. Data type mismatch (string vs UUID, number vs text)
5. Foreign key constraint violation

Always handle errors in insert/update calls:

const { data, error } = await supabase
  .from('items')
  .insert([{ user_id: userId, title: 'New Item' }])
  .select();

if (error) {
  console.error('Insert failed:', error.message);
} else {
  console.log('Inserted:', data);
}

Check Supabase Logs tab for detailed error messages.