[type/__dma*] Fix shellcheck errors

type/__dma/gencode-remote

@@ -158,7 +158,7 @@ if test -f "${__object:?}/parameter/send-test-mail"
 then
 	if grep -q '^__mail_alias/root:' "${__messages_in:?}" \
 	|| grep -q '^__dma_auth/' "${__messages_in:?}" \
-	|| $config_updated
+	|| ${config_updated}
 	then
 		cat <<-CODE
 		sendmail root <<'EOF'

type/__dma/manifest

@@ -21,7 +21,7 @@
 os=$(cat "${__global:?}/explorer/os")
 
 # Install DMA
-case $os
+case ${os}
 in
 	(alpine)
 		__package dma --state present

type/__dma_auth/explorer/state

@@ -25,7 +25,7 @@
 #   different_password: a line exists but with a different password
 #   multiple:           multiple lines matching host exist (should not happen)
 
-auth_conf=$("${__type_explorer}/auth_conf")
+auth_conf=$("${__type_explorer:?}/auth_conf")
 test -r "${auth_conf}" || exit 0
 
 awk -F'\n' '

type/__dma_auth/gencode-remote

@@ -40,7 +40,7 @@ then
 	exit 0
 fi
 
-case $state_should
+case ${state_should}
 in
 	(present)
 		test -n "${login}" || { echo '--login must be non-empty' >&2; exit 1; }