Troubleshooting: "permission denied for sequence"

Error: `permission denied for sequence labels_id_seq`

Reason: limited `insert` privileges on table means that the sequence cannot generate a new value.

Solution: Grant GraphQL the ability to use sequences in the exposed schema.

```sql
alter default privileges in schema app_public grant usage, select on sequences to app_visitor;
grant usage, select on all sequences in schema app_public to app_visitor;
```