Improve Incus and OS mismatch error handling

Refines `incus_check` to inspect `incus info` probe errors and return targeted guidance for daemon-down, permission, and uninitialized-install cases instead of a single generic start command. Updates the container OS guard to treat cross-distribution mismatches as a separate "WRONG OS" condition, with clearer remediation and dialog text to avoid impossible upgrade advice.

Author: MickLesk

incus/core.func

@@ -239,10 +239,30 @@ incus_check() {
     exit 1
   fi
 
-  # Check if incus daemon is accessible
-  if ! incus info &>/dev/null; then
-    incus_msg_error "Incus daemon is not running or not accessible."
-    incus_msg_error "Run: systemctl start incus"
+  # Check if incus daemon is accessible. The probe's own error is what tells
+  # a stopped daemon apart from a permission problem or an uninitialised
+  # install, so keep it instead of always advising "systemctl start incus".
+  local probe_err probe_rc=0
+  probe_err="$(LC_ALL=C incus info 2>&1 >/dev/null)" || probe_rc=$?
+  if ((probe_rc != 0)); then
+    case "$probe_err" in
+    *"onnection refused"* | *"o such file or directory"* | *"ailed to connect"*)
+      incus_msg_error "Incus daemon is not running."
+      incus_msg_error "Run: systemctl start incus"
+      ;;
+    *"ermission denied"* | *"not authorized"* | *"nauthorized"*)
+      incus_msg_error "No permission to reach the Incus daemon as $(id -un)."
+      incus_msg_error "Run: sudo usermod -aG incus-admin $(id -un) - then log out and back in"
+      ;;
+    *"not been initialized"* | *"o storage pool"*)
+      incus_msg_error "Incus is installed but not initialised."
+      incus_msg_error "Run: incus admin init"
+      ;;
+    *)
+      incus_msg_error "Cannot query the Incus daemon (incus info exited ${probe_rc})."
+      incus_msg_error "${probe_err:-no error output - try running: incus info}"
+      ;;
+    esac
     exit 1
   fi
 

ui/menu.func

@@ -862,8 +862,15 @@ check_container_os_guard() {
     return 0
   fi
 
-  local mismatch_detail remediation
-  if [[ "$downgraded_target" -eq 1 ]]; then
+  local mismatch_detail remediation dialog_title="OS VERSION MISMATCH"
+  if [[ "$cur_os" != "$rec_os" ]]; then
+    # Two different distributions. Their version numbers are not comparable and
+    # there is no upgrade path between them, so the version-mismatch wording
+    # produced impossible advice like "upgrade the container OS to debian 26.04".
+    dialog_title="WRONG OS"
+    mismatch_detail="This container runs ${cur_os} ${cur_ver}, but ${APP:-this script} is built for ${rec_os}.\n\nThese are different distributions - ${cur_os} cannot be upgraded to ${rec_os}, and their version numbers are unrelated.\n\nRecommended: create a new ${rec_os} ${rec_ver} container and install ${APP:-the application} there."
+    remediation="Create a new ${rec_os} ${rec_ver} container instead - ${cur_os} cannot be upgraded to ${rec_os}"
+  elif [[ "$downgraded_target" -eq 1 ]]; then
     mismatch_detail="Your container runs ${cur_os} ${cur_ver}, which is newer than what this script now targets (${rec_os} ${rec_ver}).\n\nThe target was likely lowered on purpose, e.g. because ${APP:-the app} had problems on newer OS versions - check the GitHub issues for ${APP:-this app} for details.\n\nContinuing on ${cur_ver} often still works, but isn't guaranteed. If you are unsure, ask in our Discord (https://discord.gg/3AnUqsXnmK) before continuing."
     remediation="This script now targets the older ${rec_os} ${rec_ver}. Check the GitHub issues for ${APP:-this app}, or ask in Discord (https://discord.gg/3AnUqsXnmK) if you are unsure"
   else
@@ -873,7 +880,7 @@ check_container_os_guard() {
 
   if [[ "${PHS_SILENT:-0}" != "1" ]] && command -v whiptail &>/dev/null && [ -t 0 ] && [[ "$TERM" != "dumb" ]]; then
     local choice
-    choice=$(whiptail --backtitle "Proxmox VE Helper Scripts" --title "OS VERSION MISMATCH" --menu \
+    choice=$(whiptail --backtitle "Proxmox VE Helper Scripts" --title "$dialog_title" --menu \
       "${mismatch_detail}\n\nIf you continue anyway, it may break — no support is provided in that case.\n\nContinue anyway?" \
       20 70 3 \
       "1" "No  (cancel update)" \