Revert "fix: Correctly throw errors when an invalid option is passed (#1560)"

This reverts commit 28a79b1db2.

quickget

@@ -45,7 +45,7 @@ function error_specify_os() {
 }
 
 function os_supported() {
-    if [[ ! " $(os_support) " =~ \ "${OS}"\  ]]; then
+    if [[ ! "$(os_support)" =~ ${OS} ]]; then
         echo -e "ERROR! ${OS} is not a supported OS.\n"
         os_support | fmt -w 80
         exit 1
@@ -59,7 +59,7 @@ function error_specify_release() {
 }
 
 function error_not_supported_release() {
-    if [[ ! " ${RELEASES[*]} " =~ \ "${RELEASE}"\  ]]; then
+    if [[ ! "${RELEASES[*]}" =~ ${RELEASE} ]]; then
         echo -e "ERROR! ${DISPLAY_NAME} ${RELEASE} is not a supported release.\n"
         echo -n ' - Supported releases: '
         releases_
@@ -83,17 +83,6 @@ function error_not_supported_argument() {
     exit 1
 }
 
-function is_valid_language() {
-    local I18N=""
-    local PASSED_I18N="${1}"
-    for I18N in "${I18NS[@]}"; do
-        if [[ "${I18N}" == "${PASSED_I18N}" ]]; then
-            return 0
-        fi
-    done
-    return 1
-}
-
 function handle_missing() {
     # Handle odd missing Fedora combinations
     case "${OS}" in