fix(console,computes): an unreachable host is named as the cause, not an empty list

The console page of a VM whose host does not answer said "Fail to get
console. Please check the console configuration of your VM." and logged
nothing. It now shows the connection error (to users who do not see the
hosts, that the host cannot be reached) and logs it with the VM and host.

A host's Storage, Networks, Interfaces, Filters and Secrets pages showed
the connection error and also "This host has no ...". The list is None
when it was not read, and the page shows only the error.

console/views.py

@@ -2,6 +2,7 @@
 
 import functools
 import json
+import logging
 from pathlib import Path
 
 from appsettings.settings import app_settings
@@ -12,9 +13,13 @@ from django.utils.translation import gettext_lazy as _
 from instances.models import Instance
 from instances.utils import can_open_console
 from libvirt import libvirtError
+from operations.utils import safe_text
 from vrtManager.connection import CONN_TCP, CONN_TLS
 from vrtManager.instance import wvmInstance
 from vrtManager.util import is_loopback
+from webvirtcloud.middleware import error_text
+
+logger = logging.getLogger(__name__)
 
 # one file a layout, written by dev/console_layout.py
 LAYOUTS_DIR = Path(__file__).resolve().parent / "layouts"
@@ -60,7 +65,11 @@ def console(request, compute_id, uuid):
         unreachable = instance.compute.type in (CONN_TCP, CONN_TLS) and bool(
             conn.get_console_socket() or is_loopback(conn.get_console_listener_addr())
         )
-    except (libvirtError, ValueError, IndexError):
+    except libvirtError as err:
+        # the host or the VM could not be read: the page says that, not to check the console settings
+        logger.warning("Console of %s on %s: %s", instance.name, instance.compute.name, safe_text(err))
+        return render(request, "console-error.html", {"instance": instance, "console_error": error_text(request, err)})
+    except (ValueError, IndexError):
         running = unreachable = False
         console_type = None
         console_passwd = None