refactor: fix `missingType.return` errors in system files #13159

Job	Run time
Setup PHP Version for Code Coverage	4s
Others (8.4) / Sanity Tests	2m 15s
Others (8.1) / Sanity Tests	2m 21s
Others (8.2) / Sanity Tests	4m 8s
Others (8.3) / Sanity Tests	2m 44s
SeparateProcess (8.1) / tests	3m 49s
SeparateProcess (8.2) / tests	3m 49s
SeparateProcess (8.3) / tests	3m 57s
SeparateProcess (8.4) / tests	4m 12s
CacheLive (8.2) / Cache Live Tests	2m 18s
CacheLive (8.1) / Cache Live Tests	2m 6s
CacheLive (8.3) / Cache Live Tests	1m 58s
DatabaseLive (8.1, Postgre, 8.0) / tests	3m 41s
DatabaseLive (8.2, Postgre, 8.0) / tests	3m 17s
DatabaseLive (8.3, Postgre, 8.0) / tests	2m 33s
DatabaseLive (8.4, SQLite3, 8.0) / tests	2m 58s
CacheLive (8.4) / Cache Live Tests	2m 8s
DatabaseLive (8.3, MySQLi, 8.0) / tests	5m 9s
DatabaseLive (8.4, OCI8, 8.0) / tests	7m 17s
DatabaseLive (8.1, MySQLi, 5.7) / tests	4m 27s
DatabaseLive (8.1, SQLSRV, 8.0) / tests	6m 19s
DatabaseLive (8.1, MySQLi, 8.0) / tests	4m 57s
DatabaseLive (8.4, SQLSRV, 8.0) / tests	5m 24s
DatabaseLive (8.4, Postgre, 8.0) / tests	3m 9s
DatabaseLive (8.2, OCI8, 8.0) / tests	7m 16s
DatabaseLive (8.1, SQLite3, 8.0) / tests	3m 4s
DatabaseLive (8.2, MySQLi, 8.0) / tests	5m 37s
DatabaseLive (8.2, SQLSRV, 8.0) / tests	6m 21s
DatabaseLive (8.2, SQLite3, 8.0) / tests	3m 28s
DatabaseLive (8.3, OCI8, 8.0) / tests	7m 10s
DatabaseLive (8.3, SQLSRV, 8.0) / tests	5m 25s
DatabaseLive (8.3, SQLite3, 8.0) / tests	3m 39s
DatabaseLive (8.4, MySQLi, 8.0) / tests	6m 38s
DatabaseLive (8.1, OCI8, 8.0) / tests	6m 4s
Upload coverage results to Coveralls / coveralls	33s
	2h 20m 15s

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