DeckCard population is failing on unique constraint

Need to go over the code for this to determine why this server error is occurring:

Apr 16 10:15:28 PM  Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/uvicorn/protocols/http/httptools_impl.py", line 398, in run_asgi
    result = await app(self.scope, self.receive, self.send)
  File "/usr/local/lib/python3.8/site-packages/uvicorn/middleware/proxy_headers.py", line 45, in __call__
    return await self.app(scope, receive, send)
  File "/usr/local/lib/python3.8/site-packages/fastapi/applications.py", line 199, in __call__
    await super().__call__(scope, receive, send)
  File "/usr/local/lib/python3.8/site-packages/starlette/applications.py", line 111, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/usr/local/lib/python3.8/site-packages/starlette/middleware/errors.py", line 181, in __call__
    raise exc from None
  File "/usr/local/lib/python3.8/site-packages/starlette/middleware/errors.py", line 159, in __call__
    await self.app(scope, receive, _send)
  File "/usr/local/lib/python3.8/site-packages/starlette/middleware/cors.py", line 86, in __call__
    await self.simple_response(scope, receive, send, request_headers=headers)
  File "/usr/local/lib/python3.8/site-packages/starlette/middleware/cors.py", line 142, in simple_response
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.8/site-packages/starlette/exceptions.py", line 82, in __call__
    raise exc from None
  File "/usr/local/lib/python3.8/site-packages/starlette/exceptions.py", line 71, in __call__
    await self.app(scope, receive, sender)
  File "/usr/local/lib/python3.8/site-packages/starlette/routing.py", line 566, in __call__
    await route.handle(scope, receive, send)
  File "/usr/local/lib/python3.8/site-packages/starlette/routing.py", line 227, in handle
    await self.app(scope, receive, send)
  File "/usr/local/lib/python3.8/site-packages/starlette/routing.py", line 41, in app
    response = await func(request)
  File "/usr/local/lib/python3.8/site-packages/fastapi/routing.py", line 201, in app
    raw_response = await run_endpoint_function(
  File "/usr/local/lib/python3.8/site-packages/fastapi/routing.py", line 150, in run_endpoint_function
    return await run_in_threadpool(dependant.call, **values)
  File "/usr/local/lib/python3.8/site-packages/starlette/concurrency.py", line 34, in run_in_threadpool
    return await loop.run_in_executor(None, func, *args)
  File "/usr/local/lib/python3.8/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/code/api/views/decks.py", line 371, in save_deck
    deck = create_or_update_deck(
  File "/code/api/services/deck.py", line 120, in create_or_update_deck
    session.query(Card.id, Card.stub, Card.name, Card.card_type, Card.phoenixborn)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/query.py", line 3373, in all
    return list(self)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/query.py", line 3534, in __iter__
    self.session._autoflush()
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 1633, in _autoflush
    util.raise_(e, with_traceback=sys.exc_info()[2])
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/util/compat.py", line 182, in raise_
    raise exception
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 1622, in _autoflush
    self.flush()
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 2540, in flush
    self._flush(objects)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 2682, in _flush
    transaction.rollback(_capture_exception=True)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/util/langhelpers.py", line 68, in __exit__
    compat.raise_(
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/util/compat.py", line 182, in raise_
    raise exception
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/session.py", line 2642, in _flush
    flush_context.execute()
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/unitofwork.py", line 422, in execute
    rec.execute(self)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/unitofwork.py", line 586, in execute
    persistence.save_obj(
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/persistence.py", line 239, in save_obj
    _emit_insert_statements(
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/orm/persistence.py", line 1083, in _emit_insert_statements
    c = cached_connections[connection].execute(statement, multiparams)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/engine/base.py", line 1011, in execute
    return meth(self, multiparams, params)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/sql/elements.py", line 298, in _execute_on_connection
    return connection._execute_clauseelement(self, multiparams, params)
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/engine/base.py", line 1124, in _execute_clauseelement
    ret = self._execute_context(
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/engine/base.py", line 1316, in _execute_context
    self._handle_dbapi_exception(
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/engine/base.py", line 1510, in _handle_dbapi_exception
    util.raise_(
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/util/compat.py", line 182, in raise_
    raise exception
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/engine/base.py", line 1276, in _execute_context
    self.dialect.do_execute(
  File "/usr/local/lib/python3.8/site-packages/sqlalchemy/engine/default.py", line 608, in do_execute
    cursor.execute(statement, parameters)
sqlalchemy.exc.IntegrityError: (raised as a result of Query-invoked autoflush; consider using a session.no_autoflush block if this flush is occurring prematurely)
Apr 16 10:15:28 PM  (psycopg2.errors.UniqueViolation) duplicate key value violates unique constraint "idx_168249_primary"
Apr 16 10:15:28 PM  DETAIL:  Key (deck_id, die_flag)=(9445, 8) already exists.
Apr 16 10:15:28 PM  
Apr 16 10:15:28 PM  [SQL: INSERT INTO deck_die (deck_id, die_flag, count) VALUES (%(deck_id)s, %(die_flag)s, %(count)s)]
Apr 16 10:15:28 PM  [parameters: {'deck_id': 9445, 'die_flag': 8, 'count': 4}]
Apr 16 10:15:28 PM  (Background on this error at: http://sqlalche.me/e/13/gkpj)
Apr 16 10:38:27 PM  /usr/local/lib/python3.8/site-packages/sqlalchemy/orm/persistence.py:1359: SAWarning: DELETE statement on table 'deck_card' expected to delete 1 row(s); 0 were matched.  Please set confirm_deleted_rows=False within the mapper configuration to prevent this warning.

Start in api/views/decks.py at save_deck and api/services/deck.py at create_or_update_deck, then trace the deck_die and deck_card persistence paths shown in the traceback. Reproduce the failure and inspect the unique key on deck_die and the DELETE warning. Done means deck population completes without the IntegrityError or unexpected deletion warning.