Refactor argument evaluation

quickget

@@ -854,56 +854,32 @@ if [ -n "${1}" ]; then
         list_all
     fi
 else
-    echo "ERROR! You must specify an OS:"
+    echo "ERROR! You must specify an operating system:"
     os_support
     exit 1
 fi
 
 if [ -n "${2}" ]; then
     RELEASE="${2,,}"
-else
-    echo "ERROR! You must specify an OS release name."
-    if [ "${OS}" == "elementary" ]; then
-        releases_elementary
-    elif [ "${OS}" == "freebsd" ]; then
-        releases_freebsd
-    elif [ "${OS}" == "fedora" ]; then
-        releases_fedora
-    elif [ "${OS}" == "linuxmint" ]; then
-        releases_linuxmint
-    elif [ "${OS}" == "opensuse" ]; then
-        releases_opensuse
-    elif [ "${OS}" == "macos" ]; then
-        releases_macos
-    elif [ "${OS}" == "popos" ]; then
-        releases_popos
-    elif [[ "${OS}" == *"ubuntu"* ]]; then
-        releases_ubuntu
-    elif [ "${OS}" == "windows" ]; then
-        releases_windows
-    fi
-    exit 1
-fi
+    VM_PATH="${OS}-${RELEASE}"
 
-VM_PATH="${OS}-${RELEASE}"
-
-if [ "${OS}" == "elementary" ]; then
+    if [ "${OS}" == "elementary" ]; then
         get_elementary
-elif [ "${OS}" == "macos" ]; then
+    elif [ "${OS}" == "macos" ]; then
         get_macos
-elif [[ "${OS}" == "freebsd" ]]; then
+    elif [ "${OS}" == "freebsd" ]; then
         get_freebsd
-elif [[ "${OS}" == "fedora" ]]; then
+    elif [ "${OS}" == "fedora" ]; then
         get_fedora
-elif [[ "${OS}" == "linuxmint" ]]; then
+    elif [[ "${OS}" == *"linuxmint"* ]]; then
         get_linuxmint
-elif [[ "${OS}" == "opensuse" ]]; then
+    elif [ "${OS}" == "opensuse" ]; then
         get_opensuse
-elif [[ "${OS}" == "popos" ]]; then
+    elif [ "${OS}" == "popos" ]; then
         get_popos
-elif [[ "${OS}" == *"ubuntu"* ]]; then
+    elif [[ "${OS}" == *"ubuntu"* ]]; then
         get_ubuntu
-elif [ "${OS}" == "windows" ]; then
+    elif [ "${OS}" == "windows" ]; then
         if [ -n "${3}" ]; then
             LANG_NAME="${3}"
             if [[ ! ${LANGS[*]} =~ ${LANG_NAME} ]]; then
@@ -917,8 +893,31 @@ elif [ "${OS}" == "windows" ]; then
             LANG_NAME="English International"
         fi
         get_windows "${LANG_NAME}"
-else
-    echo "ERROR! You must specify an OS:"
+    else
+        echo "ERROR! ${OS} is unknown:"
         os_support
         exit 1
+    fi
+else
+    echo "ERROR! You must specify a release for ${OS}:"
+    if [ "${OS}" == "elementary" ]; then
+        releases_elementary
+    elif [ "${OS}" == "freebsd" ]; then
+        releases_freebsd
+    elif [ "${OS}" == "fedora" ]; then
+        releases_fedora
+    elif [[ "${OS}" == *"linuxmint"* ]]; then
+        releases_linuxmint
+    elif [ "${OS}" == "opensuse" ]; then
+        releases_opensuse
+    elif [ "${OS}" == "macos" ]; then
+        releases_macos
+    elif [ "${OS}" == "popos" ]; then
+        releases_popos
+    elif [[ "${OS}" == *"ubuntu"* ]]; then
+        releases_ubuntu
+    elif [ "${OS}" == "windows" ]; then
+        releases_windows
+    fi
+    exit 1
 fi