Yoloadd a bash -n to check bash syntax near the very beginning of the test suite to crash early if there are obvious syntax errors

lib/tests.sh

@@ -16,7 +16,21 @@ _STUFF_TO_RUN_BEFORE_INITIAL_SNAPSHOT()
     # Set witness files
     set_witness_files
 
-    [[ -e $package_path/manifest.toml ]] || return
+    [[ -e $package_path/manifest.toml ]] || log_critical "The app CI / package_check doesn't support testing packaging v1 apps anymore."
+
+
+    log_title "Basic bash syntax checks"
+
+    local syntax_issue=false
+    pushd $package_path/scripts >/dev/null
+        for SCRIPT in $(ls _common.sh install remove upgrade backup restore change_url config 2>/dev/null)
+        do
+            # bash -n / noexec option allows to find syntax issues without actually running the scripts
+            # cf https://unix.stackexchange.com/questions/597743/bash-shell-noexec-option-usage-purpose
+            bash -n $SCRIPT | tee -a /proc/self/fd/3 || syntax_issue=true
+        done
+    popd >/dev/null
+    [[ $syntax_issue == true ]] && log_report_test_success || log_critical "Obvious syntax issues found which will make the scripts crash ... not running the actual tests until these are fixed"
 
     # We filter apt deps starting with $app_id to prevent stupid issues with for example cockpit and transmission where the apt package is not properly reinstalled on reinstall-after-remove test ...
     local apt_deps=$(python3 -c "import toml, sys; t = toml.loads(sys.stdin.read()); P = t['resources'].get('apt', {}).get('packages', ''); P = P.replace(',', ' ').split() if isinstance(P, str) else P; P = [p for p in P if p != '$app_id' and not p.startswith('$app_id-')]; print(' '.join(P));" < $package_path/manifest.toml)