helpers/common.sh: the minimal version is Bash 5.0

The syntax used in the Bash scripts here requires at minimum Bash 5.0.
This checks for it and reports reasonable error message instead of
failure.

There are two discovered issues with older versions of bash.

The first issue is the change of empty array expansion in Bash 4.4
resulted in empty arrays not being considered as undefined anymore. We
depended on this heavily and thus we can't easily go bellow that
version.

The second issue is that syntax `[[ -v "foo[key]" ]` works only in Bash
5.0 and newer. This checks if specific key is in the associative array.
The replacement could be `[ "${foo[key]:+_}" ]` in some cases but this
only works if value is also nonempty. Thus it makes sense to just the
more clear and reliable syntax and such depend on Bash 5.0.

compile_pkgs

@@ -14,7 +14,7 @@
 #
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
-set -e
+set -eu
 
 # Step list that is run when no commands are specified
 DEFAULT_STEPS=( "prepare" "compile" "sign" "store_hash" "stats" "pkgsrepo" "gen_junit" )

generate_lists

@@ -14,7 +14,7 @@
 #
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
-set -e
+set -eu
 
 FEED_NAME="updater-lists"
 

helpers/common.sh

@@ -14,6 +14,11 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+[[ "${BASH_VERSINFO[0]}" -ge 5 ]] || {
+	echo "Please use Bash version 5.0 or newer!" >&2
+	exit 1
+}
+
 ## Common printing functions ############
 
 # Detect tty if IS_TTY not already set