refactor: fix `missingType.return` errors in system files (#9530) #13161

Job	Run time
Setup PHP Version for Code Coverage	2s
Others (8.1) / Sanity Tests	2m 23s
Others (8.2) / Sanity Tests	3m 52s
Others (8.4) / Sanity Tests	2m 26s
Others (8.3) / Sanity Tests	2m 16s
SeparateProcess (8.1) / tests	3m 37s
SeparateProcess (8.3) / tests	3m 34s
SeparateProcess (8.2) / tests	3m 14s
SeparateProcess (8.4) / tests	3m 24s
DatabaseLive (8.1, MySQLi, 8.0) / tests	4m 12s
DatabaseLive (8.3, SQLite3, 8.0) / tests	2m 52s
DatabaseLive (8.2, OCI8, 8.0) / tests	6m 58s
DatabaseLive (8.2, Postgre, 8.0) / tests	3m 15s
DatabaseLive (8.4, SQLite3, 8.0) / tests	2m 55s
DatabaseLive (8.2, MySQLi, 8.0) / tests	6m 14s
DatabaseLive (8.4, MySQLi, 8.0) / tests	3m 54s
DatabaseLive (8.2, SQLSRV, 8.0) / tests	6m 30s
DatabaseLive (8.1, OCI8, 8.0) / tests	6m 41s
DatabaseLive (8.2, SQLite3, 8.0) / tests	3m 14s
DatabaseLive (8.1, SQLSRV, 8.0) / tests	5m 8s
DatabaseLive (8.3, SQLSRV, 8.0) / tests	5m 57s
DatabaseLive (8.4, Postgre, 8.0) / tests	2m 51s
DatabaseLive (8.3, Postgre, 8.0) / tests	3m 12s
DatabaseLive (8.1, Postgre, 8.0) / tests	2m 46s
DatabaseLive (8.4, SQLSRV, 8.0) / tests	5m 14s
DatabaseLive (8.1, MySQLi, 5.7) / tests	3m 38s
DatabaseLive (8.3, OCI8, 8.0) / tests	6m 20s
DatabaseLive (8.4, OCI8, 8.0) / tests	6m 9s
DatabaseLive (8.3, MySQLi, 8.0) / tests	4m 53s
DatabaseLive (8.1, SQLite3, 8.0) / tests	2m 34s
CacheLive (8.2) / Cache Live Tests	2m 17s
CacheLive (8.1) / Cache Live Tests	1m 55s
CacheLive (8.4) / Cache Live Tests	2m 18s
CacheLive (8.3) / Cache Live Tests	1m 56s
Upload coverage results to Coveralls / coveralls	34s
	2h 9m 15s

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