How to handle errors in getopt - bash

Question

Based on tutorials I found here and here getopt should provide me with information about errors using some combination of characters :?*.
But when I used this code:
#!/bin/bash
eval set -- "$(getopt -o hspna: --long help,server,project,name-prefix,action: -- "$#")"
while [ : ]; do
case "$1" in
-s | --server)
echo "Setting server"
shift
;;
-p | --project)
echo "Setting project"
shift
;;
-n | --name-prefix)
echo "Setting name prefix"
shift
;;
-a | --action)
echo "Setting action"
shift
;;
--)
shift
break
;;
-h | --help)
echo "Providing help 1"
exit
;;
:)
echo "Providing help 2"
exit
;;
?)
echo "Providing help 3"
exit
;;
*)
echo "Providing help 4"
exit
;;
esac
done
echo $#
echo "Configured"
exit
Then following command that was supposed to show an error gave me the following output:
$ ./debug.sh -a -s -b -- foo bar baz
getopt: invalid option -- 'b'
Setting action
Setting server
foo bar baz
Configured
I was expecting that:
Providing help 2 will appear due to -a missing a value
Providing help 3 will appear due to -b not being a valid parameter
Providing help 4 will appear due to overall errors
Configured should never appear since the previous 3 points have an exit
But none of the above was true.
Also when testing further even more things did not work as expected.
# Expecting error due to missing value for `-a` but instead everything worked fine
$ ./debug.sh -a -s
Setting action
Setting server
Configured
# This time I expected everything to work fine, since I provided `X` as value of `-a`, but error was shown.
$ ./debug.sh -aX
Setting action
Providing help 3
What am I doing wrong?

Answer 1

What am I doing wrong?
Util-linux getopt prints and handles errors.
if ! args="$(getopt \
-n your_command \
-o hspna: \
--long help,server,project,name-prefix,action: \
-- "$#"\
)"; then
exit 1
fi
eval "set -- $args"
...
$ ./util -a
your_command: option requires an argument -- 'a'
I was expecting that:
I do not understand why. There is no such documentation in getopt. No, getopt will not output ? nor :. You can handle your (as the author of the program) errors, like you forgot to handle the option in case that you have given to getopt - you handle that with *).
The ? is a glob that matches any character. Because you forgot a shift after esac before done, X remains in $1, which is one character and is matched by ?). You meant '?'). This should go into *) case, and you should print yourself an error message.
Example, subjective in my style that I use (many people do not like set -eu):
set -euo pipefail
args=$(getopt -o ab -- "$#")
eval "set -- $args"
aflag=0
while (($#)); do
case "$1" in
-a) afloag=1; ;;
--) shift; break;
*) echo "Och no, I forgot about -b, or some other error!" >&2; exit 1; ;;
easc
shift
done