fixing https://github.com/koalaman/shellcheck/wiki/SC2181 problems

dnsapi/dns_nm.sh

@@ -34,11 +34,10 @@ dns_nm_add() {
 
   zone="$(echo $fulldomain | _egrep_o "[^.]+.[^.]+$")"
   get="https://namemaster.de/api/api.php?User=$NM_user&Password=$NM_md5&Antwort=csv&Int=0&Typ=ACME&Zone=$zone&hostname=$fulldomain&TXT=$txt_value&Action=Auto&Lifetime=3600"
-  erg="$(_get "$get")"
 
-  exit_code="$?"
-  if [ "$exit_code" != 0 ]; then
-    _err "error Ading $zone TXT: $txt_value"
+  if !   erg="$(_get "$get")"
+  then
+    _err "error Deleting $zone TXT: $txt_value"
     _err "Error $exit_code"
     return 1
   fi
@@ -70,10 +69,9 @@ dns_nm_rm() {
 
   zone="$(echo $fulldomain | _egrep_o "[^.]+.[^.]+$")"
   get="https://namemaster.de/api/api.php?User=$NM_user&Password=$NM_md5&Antwort=csv&Int=0&Typ=TXT&Zone=$zone&hostname=$fulldomain&TXT=$txt_value&Action=Delete_IN&TTL=0"
-  erg="$(_get "$get")"
 
-  exit_code="$?"
-  if [ "$exit_code" != "0" ]; then
+  if !   erg="$(_get "$get")"
+  then
     _err "error Deleting $zone TXT: $txt_value"
     _err "Error $exit_code"
     return 1