fix(logs): failures name their job, VM and user; the new VM form shows a list it could not load

- A failed cancel hook logged "worker task cancel failed": it now names
  the job, its kind, resource and user, with the traceback for a fault
  of the panel.
- novncd logged "Console connection failed" without the VM or the user.
- django-axes wrote four INFO lines a login ("Reset 0 access
  attempts"...); logins are on the Logs page, so it logs warnings only.
- The new VM form's machine types and disk buses answered 200 with an
  empty object when libvirt failed, and nothing was logged: the list
  stayed empty, the form could not go on and said nothing. They answer
  400 with the error, as the pool's volume list does, the warning is
  logged with the compute, and the form's lists show an error they get
  with the page's messages.

instances/tests/test_create_page_js.py

@@ -45,7 +45,8 @@ const field = sel => fields[sel] ??= new El();
 const rows = list => field(list).children;
 const document = {getElementById: id => templates[id], querySelector: field, querySelectorAll: sel => all[sel] ?? []};
 const replies = [];
-const $ = Object.assign(() => ({ready: f => f()}), {getJSON: (url, f) => { replies.push(f); return {}; }});
+const $ = Object.assign(() => ({ready: f => f()}), {getJSON: (url, f) => { replies.push(f); return {fail() { return this; }}; }});
+const showLoadError = () => {};
 const Option = function (text, value) { return {text, value}; };
 // TomSelect: records its added options and items, and calls the page's
 // callbacks as TomSelect does (a silent addItem still calls onItemAdd)
@@ -90,7 +91,7 @@ class CreatePageScriptTests(TestCase):
         compute, page = self.page()
         buses_url = html.fromstring(page).get_element_by_id("create-vm-form").get("data-buses-url")
         out = node(f"const document = {{querySelector: () => ({{dataset: {{busesUrl: {json.dumps(buses_url)}}}}})}};"
-                   "let asked; const $ = {getJSON: url => { asked = url; }};"
+                   "let asked; const $ = {getJSON: url => { asked = url; return {fail() {}}; }}; const showLoadError = null;"
                    + functions("form_data", "load_list", "load_buses")
                    + "load_buses({replaceChildren() {}}, 'cdrom'); console.log(JSON.stringify(asked));")
         self.assertEqual(out, reverse("buses", args=[compute.id, "i686", "pc", "cdrom"]))
@@ -98,14 +99,17 @@ class CreatePageScriptTests(TestCase):
     @unittest.skipUnless(shutil.which("node"), "node is not installed")
     def test_a_list_is_empty_while_it_loads_and_a_newer_load_aborts_the_older(self):
         out = node("const document = {querySelector: () => ({dataset: {busesUrl: '/__disk__/'}})}; const requests = [];"
-                   "const $ = {getJSON: (url, fill) => { const r = {fill, abort() { r.aborted = true; }}; requests.push(r); return r; }};"
+                   "const $ = {getJSON: (url, fill) => { const r = {fill, abort() { r.aborted = true; }, fail(f) { r.failed = f; return r; }}; requests.push(r); return r; }};"
+                   "const showLoadError = () => {};"
                    "const Option = function (text) { this.text = text; };"
                    "const bus = {children: ['ide'], replaceChildren(...items) { this.children = items; }};"
                    + functions("form_data", "load_list", "load_buses")
                    + "load_buses(bus, 'disk'); const loading = bus.children; load_buses(bus, 'cdrom');"
                    "requests[1].fill({bus: ['sata']});"
-                   "console.log(JSON.stringify({loading, aborted: requests.map(r => !!r.aborted), filled: bus.children.map(o => o.text)}));")
-        self.assertEqual(out, {"loading": [], "aborted": [True, False], "filled": ["sata"]})
+                   "console.log(JSON.stringify({loading, aborted: requests.map(r => !!r.aborted), filled: bus.children.map(o => o.text),"
+                   " reported: requests.every(r => r.failed === showLoadError)}));")
+        # a load the host refused says why on the page
+        self.assertEqual(out, {"loading": [], "aborted": [True, False], "filled": ["sata"], "reported": True})
 
     def test_the_form_has_one_mac_field(self):
         _, page = self.page()

instances/tests/test_create_wizard_url.py

@@ -53,7 +53,8 @@ class CreateWizardUrlTests(TestCase):
             js = ("const next = {disabled: false}, select = {dataset: {machinesUrl: '/__arch__/'}, replaceChildren() {}};"
                   "const document = {querySelector: sel => sel === '#next' ? next : select};"
                   "const Option = function () {};"
-                  f"const $ = {{getJSON: (url, f) => f({{machines: {machines!r}}})}};"
+                  f"const $ = {{getJSON: (url, f) => {{ f({{machines: {machines!r}}}); return {{fail() {{}}}}; }}}};"
+                  "const showLoadError = null;"
                   f"{load_machines} load_machines('x86_64'); console.log(next.disabled);")
             out = subprocess.run(["node", "-e", js], capture_output=True, text=True, timeout=30)
             with self.subTest(machines=machines):
@@ -65,7 +66,8 @@ class CreateWizardUrlTests(TestCase):
         js = ("const next = {}, select = {dataset: {machinesUrl: '/__arch__/'}, children: ['pc'], replaceChildren(...items) { this.children = items; }};"
               "const document = {querySelector: sel => sel === '#next' ? next : select};"
               "const Option = function (text) { this.text = text; }; const requests = [];"
-              "const $ = {getJSON: (url, fill) => { const r = {fill, abort() { r.aborted = true; }}; requests.push(r); return r; }};"
+              "const $ = {getJSON: (url, fill) => { const r = {fill, abort() { r.aborted = true; }, fail() { return r; }}; requests.push(r); return r; }};"
+              "const showLoadError = null;"
               f"{load_machines} load_machines('x86_64'); const loading = select.children; load_machines('aarch64');"
               "requests[1].fill({machines: ['virt']});"
               "console.log(JSON.stringify({loading, aborted: requests.map(r => !!r.aborted), filled: select.children.map(o => o.text)}));")