Add TRAP to the installer

Signed-off-by: Christian König <github@yubiuser.dev>

automated install/basic-install.sh

@@ -25,6 +25,9 @@ set -e
 # When using "su" an incomplete PATH could be passed: https://github.com/pi-hole/pi-hole/issues/3209
 export PATH+=':/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin'
 
+# Trap any errors, then exit
+trap abort INT QUIT TERM
+
 ######## VARIABLES #########
 # For better maintainability, we store as much information that can change in variables
 # This allows us to make a change in one place that can propagate to all instances of the variable
@@ -195,6 +198,15 @@ show_ascii_berry() {
 "
 }
 
+abort() {
+    echo -e "\\n\\n  ${COL_LIGHT_RED}Installation was interrupted${COL_NC}\\n"
+    echo -e "Pi-hole's dependencies might be already installed. If you want to remove them you can try to\\n"
+    echo -e "a) run 'pihole uninstall' \\n"
+    echo -e "b) Remove the meta-package 'pihole-meta' manually \\n"
+    echo -e "E.g. sudo apt-get remove pihole-meta && apt-get autoremove \\n"
+    exit 1
+}
+
 is_command() {
     # Checks to see if the given command (passed as a string argument) exists on the system.
     # The function returns 0 (success) if the command exists, and 1 if it doesn't.