Function assertValidTimezone

Returns asserts potentialTimezone is
    | "Africa/Abidjan"
    | "Africa/Accra"
    | "Africa/Addis_Ababa"
    | "Africa/Algiers"
    | "Africa/Asmara"
    | "Africa/Bamako"
    | "Africa/Bangui"
    | "Africa/Banjul"
    | "Africa/Bissau"
    | "Africa/Blantyre"
    | "Africa/Brazzaville"
    | "Africa/Bujumbura"
    | "Africa/Cairo"
    | "Africa/Casablanca"
    | "Africa/Ceuta"
    | "Africa/Conakry"
    | "Africa/Dakar"
    | "Africa/Dar_es_Salaam"
    | "Africa/Djibouti"
    | "Africa/Douala"
    | "Africa/El_Aaiun"
    | "Africa/Freetown"
    | "Africa/Gaborone"
    | "Africa/Harare"
    | "Africa/Johannesburg"
    | "Africa/Juba"
    | "Africa/Kampala"
    | "Africa/Khartoum"
    | "Africa/Kigali"
    | "Africa/Kinshasa"
    | "Africa/Lagos"
    | "Africa/Libreville"
    | "Africa/Lome"
    | "Africa/Luanda"
    | "Africa/Lubumbashi"
    | "Africa/Lusaka"
    | "Africa/Malabo"
    | "Africa/Maputo"
    | "Africa/Maseru"
    | "Africa/Mbabane"
    | "Africa/Mogadishu"
    | "Africa/Monrovia"
    | "Africa/Nairobi"
    | "Africa/Ndjamena"
    | "Africa/Niamey"
    | "Africa/Nouakchott"
    | "Africa/Ouagadougou"
    | "Africa/Porto-Novo"
    | "Africa/Sao_Tome"
    | "Africa/Timbuktu"
    | "Africa/Tripoli"
    | "Africa/Tunis"
    | "Africa/Windhoek"
    | "America/Adak"
    | "America/Anchorage"
    | "America/Anguilla"
    | "America/Antigua"
    | "America/Araguaina"
    | "America/Argentina/Buenos_Aires"
    | "America/Argentina/Catamarca"
    | "America/Argentina/ComodRivadavia"
    | "America/Argentina/Cordoba"
    | "America/Argentina/Jujuy"
    | "America/Argentina/La_Rioja"
    | "America/Argentina/Mendoza"
    | "America/Argentina/Rio_Gallegos"
    | "America/Argentina/Salta"
    | "America/Argentina/San_Juan"
    | "America/Argentina/San_Luis"
    | "America/Argentina/Tucuman"
    | "America/Argentina/Ushuaia"
    | "America/Aruba"
    | "America/Asuncion"
    | "America/Atikokan"
    | "America/Bahia"
    | "America/Bahia_Banderas"
    | "America/Barbados"
    | "America/Belem"
    | "America/Belize"
    | "America/Blanc-Sablon"
    | "America/Boa_Vista"
    | "America/Bogota"
    | "America/Boise"
    | "America/Cambridge_Bay"
    | "America/Campo_Grande"
    | "America/Cancun"
    | "America/Caracas"
    | "America/Cayenne"
    | "America/Cayman"
    | "America/Chicago"
    | "America/Chihuahua"
    | "America/Coral_Harbour"
    | "America/Costa_Rica"
    | "America/Creston"
    | "America/Cuiaba"
    | "America/Curacao"
    | "America/Danmarkshavn"
    | "America/Dawson"
    | "America/Dawson_Creek"
    | "America/Denver"
    | "America/Detroit"
    | "America/Dominica"
    | "America/Edmonton"
    | "America/Eirunepe"
    | "America/El_Salvador"
    | "America/Ensenada"
    | "America/Fort_Nelson"
    | "America/Fortaleza"
    | "America/Glace_Bay"
    | "America/Goose_Bay"
    | "America/Grand_Turk"
    | "America/Grenada"
    | "America/Guadeloupe"
    | "America/Guatemala"
    | "America/Guayaquil"
    | "America/Guyana"
    | "America/Halifax"
    | "America/Havana"
    | "America/Hermosillo"
    | "America/Indiana/Indianapolis"
    | "America/Indiana/Knox"
    | "America/Indiana/Marengo"
    | "America/Indiana/Petersburg"
    | "America/Indiana/Tell_City"
    | "America/Indiana/Vevay"
    | "America/Indiana/Vincennes"
    | "America/Indiana/Winamac"
    | "America/Inuvik"
    | "America/Iqaluit"
    | "America/Jamaica"
    | "America/Juneau"
    | "America/Kentucky/Louisville"
    | "America/Kentucky/Monticello"
    | "America/La_Paz"
    | "America/Lima"
    | "America/Los_Angeles"
    | "America/Maceio"
    | "America/Managua"
    | "America/Manaus"
    | "America/Martinique"
    | "America/Matamoros"
    | "America/Mazatlan"
    | "America/Menominee"
    | "America/Merida"
    | "America/Metlakatla"
    | "America/Mexico_City"
    | "America/Miquelon"
    | "America/Moncton"
    | "America/Monterrey"
    | "America/Montevideo"
    | "America/Montreal"
    | "America/Montserrat"
    | "America/Nassau"
    | "America/New_York"
    | "America/Nipigon"
    | "America/Nome"
    | "America/Noronha"
    | "America/North_Dakota/Beulah"
    | "America/North_Dakota/Center"
    | "America/North_Dakota/New_Salem"
    | "America/Nuuk"
    | "America/Ojinaga"
    | "America/Panama"
    | "America/Pangnirtung"
    | "America/Paramaribo"
    | "America/Phoenix"
    | "America/Port-au-Prince"
    | "America/Port_of_Spain"
    | "America/Porto_Velho"
    | "America/Puerto_Rico"
    | "America/Punta_Arenas"
    | "America/Rainy_River"
    | "America/Rankin_Inlet"
    | "America/Recife"
    | "America/Regina"
    | "America/Resolute"
    | "America/Rio_Branco"
    | "America/Rosario"
    | "America/Santarem"
    | "America/Santiago"
    | "America/Santo_Domingo"
    | "America/Sao_Paulo"
    | "America/Scoresbysund"
    | "America/Sitka"
    | "America/St_Johns"
    | "America/St_Kitts"
    | "America/St_Lucia"
    | "America/St_Thomas"
    | "America/St_Vincent"
    | "America/Swift_Current"
    | "America/Tegucigalpa"
    | "America/Thule"
    | "America/Thunder_Bay"
    | "America/Tijuana"
    | "America/Toronto"
    | "America/Tortola"
    | "America/Vancouver"
    | "America/Whitehorse"
    | "America/Winnipeg"
    | "America/Yakutat"
    | "America/Yellowknife"
    | "Antarctica/Casey"
    | "Antarctica/Davis"
    | "Antarctica/DumontDUrville"
    | "Antarctica/Macquarie"
    | "Antarctica/Mawson"
    | "Antarctica/McMurdo"
    | "Antarctica/Palmer"
    | "Antarctica/Rothera"
    | "Antarctica/Syowa"
    | "Antarctica/Troll"
    | "Antarctica/Vostok"
    | "Asia/Aden"
    | "Asia/Almaty"
    | "Asia/Amman"
    | "Asia/Anadyr"
    | "Asia/Aqtau"
    | "Asia/Aqtobe"
    | "Asia/Ashgabat"
    | "Asia/Atyrau"
    | "Asia/Baghdad"
    | "Asia/Bahrain"
    | "Asia/Baku"
    | "Asia/Bangkok"
    | "Asia/Barnaul"
    | "Asia/Beirut"
    | "Asia/Bishkek"
    | "Asia/Brunei"
    | "Asia/Chita"
    | "Asia/Choibalsan"
    | "Asia/Chongqing"
    | "Asia/Colombo"
    | "Asia/Damascus"
    | "Asia/Dhaka"
    | "Asia/Dili"
    | "Asia/Dubai"
    | "Asia/Dushanbe"
    | "Asia/Famagusta"
    | "Asia/Gaza"
    | "Asia/Harbin"
    | "Asia/Hebron"
    | "Asia/Ho_Chi_Minh"
    | "Asia/Hong_Kong"
    | "Asia/Hovd"
    | "Asia/Irkutsk"
    | "Asia/Jakarta"
    | "Asia/Jayapura"
    | "Asia/Jerusalem"
    | "Asia/Kabul"
    | "Asia/Kamchatka"
    | "Asia/Karachi"
    | "Asia/Kashgar"
    | "Asia/Kathmandu"
    | "Asia/Khandyga"
    | "Asia/Kolkata"
    | "Asia/Krasnoyarsk"
    | "Asia/Kuala_Lumpur"
    | "Asia/Kuching"
    | "Asia/Kuwait"
    | "Asia/Macau"
    | "Asia/Magadan"
    | "Asia/Makassar"
    | "Asia/Manila"
    | "Asia/Muscat"
    | "Asia/Nicosia"
    | "Asia/Novokuznetsk"
    | "Asia/Novosibirsk"
    | "Asia/Omsk"
    | "Asia/Oral"
    | "Asia/Phnom_Penh"
    | "Asia/Pontianak"
    | "Asia/Pyongyang"
    | "Asia/Qatar"
    | "Asia/Qostanay"
    | "Asia/Qyzylorda"
    | "Asia/Riyadh"
    | "Asia/Sakhalin"
    | "Asia/Samarkand"
    | "Asia/Seoul"
    | "Asia/Shanghai"
    | "Asia/Singapore"
    | "Asia/Srednekolymsk"
    | "Asia/Taipei"
    | "Asia/Tashkent"
    | "Asia/Tbilisi"
    | "Asia/Tehran"
    | "Asia/Tel_Aviv"
    | "Asia/Thimphu"
    | "Asia/Tokyo"
    | "Asia/Tomsk"
    | "Asia/Ulaanbaatar"
    | "Asia/Urumqi"
    | "Asia/Ust-Nera"
    | "Asia/Vientiane"
    | "Asia/Vladivostok"
    | "Asia/Yakutsk"
    | "Asia/Yangon"
    | "Asia/Yekaterinburg"
    | "Asia/Yerevan"
    | "Atlantic/Azores"
    | "Atlantic/Bermuda"
    | "Atlantic/Canary"
    | "Atlantic/Cape_Verde"
    | "Atlantic/Faroe"
    | "Atlantic/Jan_Mayen"
    | "Atlantic/Madeira"
    | "Atlantic/Reykjavik"
    | "Atlantic/South_Georgia"
    | "Atlantic/St_Helena"
    | "Atlantic/Stanley"
    | "Australia/Adelaide"
    | "Australia/Brisbane"
    | "Australia/Broken_Hill"
    | "Australia/Currie"
    | "Australia/Darwin"
    | "Australia/Eucla"
    | "Australia/Hobart"
    | "Australia/Lindeman"
    | "Australia/Lord_Howe"
    | "Australia/Melbourne"
    | "Australia/Perth"
    | "Australia/Sydney"
    | "CET"
    | "CST6CDT"
    | "EET"
    | "EST"
    | "EST5EDT"
    | "Etc/GMT+1"
    | "Etc/GMT+10"
    | "Etc/GMT+11"
    | "Etc/GMT+12"
    | "Etc/GMT+2"
    | "Etc/GMT+3"
    | "Etc/GMT+4"
    | "Etc/GMT+5"
    | "Etc/GMT+6"
    | "Etc/GMT+7"
    | "Etc/GMT+8"
    | "Etc/GMT+9"
    | "Etc/GMT-1"
    | "Etc/GMT-10"
    | "Etc/GMT-11"
    | "Etc/GMT-12"
    | "Etc/GMT-13"
    | "Etc/GMT-14"
    | "Etc/GMT-2"
    | "Etc/GMT-3"
    | "Etc/GMT-4"
    | "Etc/GMT-5"
    | "Etc/GMT-6"
    | "Etc/GMT-7"
    | "Etc/GMT-8"
    | "Etc/GMT-9"
    | "Europe/Amsterdam"
    | "Europe/Andorra"
    | "Europe/Astrakhan"
    | "Europe/Athens"
    | "Europe/Belfast"
    | "Europe/Belgrade"
    | "Europe/Berlin"
    | "Europe/Brussels"
    | "Europe/Bucharest"
    | "Europe/Budapest"
    | "Europe/Chisinau"
    | "Europe/Copenhagen"
    | "Europe/Dublin"
    | "Europe/Gibraltar"
    | "Europe/Guernsey"
    | "Europe/Helsinki"
    | "Europe/Isle_of_Man"
    | "Europe/Istanbul"
    | "Europe/Jersey"
    | "Europe/Kaliningrad"
    | "Europe/Kirov"
    | "Europe/Kyiv"
    | "Europe/Lisbon"
    | "Europe/Ljubljana"
    | "Europe/London"
    | "Europe/Luxembourg"
    | "Europe/Madrid"
    | "Europe/Malta"
    | "Europe/Minsk"
    | "Europe/Monaco"
    | "Europe/Moscow"
    | "Europe/Oslo"
    | "Europe/Paris"
    | "Europe/Prague"
    | "Europe/Riga"
    | "Europe/Rome"
    | "Europe/Samara"
    | "Europe/Sarajevo"
    | "Europe/Saratov"
    | "Europe/Simferopol"
    | "Europe/Skopje"
    | "Europe/Sofia"
    | "Europe/Stockholm"
    | "Europe/Tallinn"
    | "Europe/Tirane"
    | "Europe/Tiraspol"
    | "Europe/Ulyanovsk"
    | "Europe/Uzhgorod"
    | "Europe/Vaduz"
    | "Europe/Vienna"
    | "Europe/Vilnius"
    | "Europe/Volgograd"
    | "Europe/Warsaw"
    | "Europe/Zagreb"
    | "Europe/Zaporozhye"
    | "Europe/Zurich"
    | "HST"
    | "Indian/Antananarivo"
    | "Indian/Chagos"
    | "Indian/Christmas"
    | "Indian/Cocos"
    | "Indian/Comoro"
    | "Indian/Kerguelen"
    | "Indian/Mahe"
    | "Indian/Maldives"
    | "Indian/Mauritius"
    | "Indian/Mayotte"
    | "Indian/Reunion"
    | "MET"
    | "MST"
    | "MST7MDT"
    | "PST8PDT"
    | "Pacific/Apia"
    | "Pacific/Auckland"
    | "Pacific/Bougainville"
    | "Pacific/Chatham"
    | "Pacific/Chuuk"
    | "Pacific/Easter"
    | "Pacific/Efate"
    | "Pacific/Enderbury"
    | "Pacific/Fakaofo"
    | "Pacific/Fiji"
    | "Pacific/Funafuti"
    | "Pacific/Galapagos"
    | "Pacific/Gambier"
    | "Pacific/Guadalcanal"
    | "Pacific/Guam"
    | "Pacific/Honolulu"
    | "Pacific/Johnston"
    | "Pacific/Kanton"
    | "Pacific/Kiritimati"
    | "Pacific/Kosrae"
    | "Pacific/Kwajalein"
    | "Pacific/Majuro"
    | "Pacific/Marquesas"
    | "Pacific/Midway"
    | "Pacific/Nauru"
    | "Pacific/Niue"
    | "Pacific/Norfolk"
    | "Pacific/Noumea"
    | "Pacific/Pago_Pago"
    | "Pacific/Palau"
    | "Pacific/Pitcairn"
    | "Pacific/Pohnpei"
    | "Pacific/Port_Moresby"
    | "Pacific/Rarotonga"
    | "Pacific/Saipan"
    | "Pacific/Tahiti"
    | "Pacific/Tarawa"
    | "Pacific/Tongatapu"
    | "Pacific/Wake"
    | "Pacific/Wallis"
    | "UTC"
    | "WET"