Make migrations (mostly) idempotent.

config/sql/session_ids.sql

@@ -2,7 +2,7 @@
 
 -- DROP TABLE public.session_ids;
 
-CREATE TABLE public.session_ids
+CREATE TABLE IF NOT EXISTS public.session_ids
 (
   id text NOT NULL,
   email text,
@@ -10,13 +10,13 @@ CREATE TABLE public.session_ids
   CONSTRAINT session_ids_pkey PRIMARY KEY (id)
 );
 
-GRANT ALL ON TABLE public.session_ids TO kemal;
+GRANT ALL ON TABLE public.session_ids TO current_user;
 
 -- Index: public.session_ids_id_idx
 
 -- DROP INDEX public.session_ids_id_idx;
 
-CREATE INDEX session_ids_id_idx
+CREATE INDEX IF NOT EXISTS session_ids_id_idx
   ON public.session_ids
   USING btree
   (id COLLATE pg_catalog."default");