MDL-86177 task: ensure tasks are runnable in indicator output.

Also fix case where task indicator progress data no longer exists,
which lead to exceptions when encountered, breaking the gradebook.

grade/tests/behat/grade_async_regrade.feature

@@ -100,7 +100,6 @@ Feature: Asynchronous regrade on a large course
   Scenario: Task indicator progresses and redirects when the task is run.
     When I am on the "Test course 1" "grades > Grader report > View" page logged in as teacher1
     And I should see "The report will update automatically. You don't need to do anything."
-    And I should not see "Run now"
     And I should not see "0.0%"
     And "user-grades" "table" should not exist
     And I run all adhoc tasks
@@ -113,12 +112,6 @@ Feature: Asynchronous regrade on a large course
     And "user-grades" "table" should exist
     And "40.00" "text" should exist in the "student1@example.com" "table_row"
 
-  Scenario: Admin should see a "Run now" button in the task indicator
-    When I am on the "Test course 1" "grades > Grader report > View" page logged in as admin
-    And I should see "The report will update automatically. You don't need to do anything."
-    And I should not see "0.0%"
-    And I should see "Run now"
-
   Scenario: Making changes on course with less than 100 grades performs the regrade synchronously, no indicator is shown.
     Given I am on the "Test assignment 2" "assign activity editing" page logged in as teacher1
     And I expand all fieldsets

lib/classes/output/task_indicator.php

@@ -98,6 +98,7 @@ class task_indicator implements renderable, templatable {
             if (
                 array_key_exists('task', plugin_manager::instance()->get_present_plugins('tool'))
                 && is_null($this->taskrecord->timestarted)
+                && \core\task\manager::is_runnable()
                 && has_capability('moodle/site:config', system::instance())
             ) {
                 $this->runurl = new url('/admin/tool/task/run_adhoctasks.php', ['id' => $this->taskrecord->id]);
@@ -124,13 +125,15 @@ class task_indicator implements renderable, templatable {
         if ($this->taskrecord) {
             $export['heading'] = $this->heading;
             $export['message'] = $this->message;
-            $export['progress'] = $this->progressbar->export_for_template($output);
             $export['icon'] = $this->icon ? $this->icon->export_for_template($output) : '';
             $export['redirecturl'] = $this->redirecturl?->out();
             $export['extraclasses'] = implode(' ', $this->extraclasses);
             $export['runurl'] = $this->runurl?->out();
             $export['runlabel'] = $this->runlabel;
-            $this->progressbar->init_js();
+            if ($this->progressbar !== null) {
+                $export['progress'] = $this->progressbar->export_for_template($output);
+                $this->progressbar->init_js();
+            }
         }
         return $export;
     }

lib/templates/task_indicator.mustache

@@ -49,12 +49,12 @@
         <h2>{{heading}}</h2>
         <p>{{message}}</p>
     </div>
-    {{#runurl}}
-        <p class="text-center">
-            <a class="runlink btn btn-primary" href="{{runurl}}" data-idnumber="{{progress.idnumber}}">{{runlabel}}</a>
-        </p>
-    {{/runurl}}
     {{#progress}}
+        {{#runurl}}
+            <p class="text-center">
+                <a class="runlink btn btn-primary" href="{{runurl}}" data-idnumber="{{idnumber}}">{{runlabel}}</a>
+            </p>
+        {{/runurl}}
         {{>core/progress_bar}}
     {{/progress}}