Use the recommended set in scripts

scripts/install

@@ -1,6 +1,5 @@
 #!/bin/bash
-set -e
-# Constants
+set -eu
 
 # Retrieve arguments
 domain=$1

scripts/remove

@@ -1,5 +1,5 @@
 #!/bin/bash
-set -e
+set -u
 
 # supervisord and other Debian dependencies remain installed
 # there is no way to know if they are used by other programs

scripts/upgrade

@@ -1,5 +1,5 @@
 #!/bin/bash
-set -e
+set -eu
 app=$YNH_APP_INSTANCE_NAME