Update package_manager_exists.sh

Author: CLHatch

.scripts/package_manager_exists.sh

@@ -5,9 +5,11 @@ IFS=$'\n\t'
 package_manager_exists() {
     local -l PackageManager=${1-}
 
-    [[ -n ${PackageManager-} ]] &&
-        run_script 'package_manager_is_valid' "${PackageManager}" &&
-        [[ -n $(command -v "${PM_PACKAGE_MANAGER_COMMAND["${PackageManager}"]}") ]]
+    [[ -n ${PackageManager-} ]] || return 1
+    run_script 'package_manager_is_valid' "${PackageManager}" || return 1
+    [[ -n $(command -v "${PM_PACKAGE_MANAGER_COMMAND["${PackageManager}"]}") || return 1
+
+    return 0
 }
 
 test_package_manager_exists() {