When you create a new questionnaire you have an option to base it on an existing template. The list of templates is shown with radio buttons and links to each template. If you try to follow a link to one of the templates, you will get a blank screen (Moodle 2.8) or an error (Moodle 2.9). To recreate:

1. In Moodle 2.9, using the Clean theme, add a Questionnaire to a course
2. Under "Advanced settings" change the type to "Template"
3. While adding a second Questionnaire to the course, open the "Content options" area
4. Confirm that you see the first Questionnaire listed as an available template
5. Click on the link to the first Questionnaire (not the radio button, but the link itself)
6. You should presumably see a preview of the Questionnaire
7. Instead you will see an error message

Error Message:

Coding error detected, it must be fixed by a programmer: The course you passed to $PAGE->set_cm does not correspond to the $cm.

Stack trace with debugging on:

{{Debug info:
Error code: codingerror
Stack trace:

line 1000 of /lib/pagelib.php: coding_exception thrown
line 3953 of /lib/navigationlib.php: call to moodle_page->set_cm()
line 3466 of /lib/navigationlib.php: call to settings_navigation->load_module_settings()
line 719 of /lib/pagelib.php: call to settings_navigation->initialise()
line 768 of /lib/pagelib.php: call to moodle_page->magic_get_settingsnav()
line 3111 of /lib/navigationlib.php: call to moodle_page->__get()
line 3155 of /lib/navigationlib.php: call to navbar->has_items()
line 35 of /theme/bootstrapbase/renderers/core_renderer.php: call to navbar->get_items()
line 4049 of /lib/outputrenderers.php: call to theme_bootstrapbase_core_renderer->navbar()
line 72 of /theme/bootstrapbase/layout/popup.php: call to core_renderer->full_header()
line 1015 of /lib/outputrenderers.php: call to include()
line 945 of /lib/outputrenderers.php: call to core_renderer->render_page_layout()
line ? of unknownfile: call to core_renderer->header()
line 1816 of /lib/setuplib.php: call to call_user_func_array()
line 116 of /mod/questionnaire/preview.php: call to bootstrap_renderer->__call()
line 116 of /mod/questionnaire/preview.php: call to bootstrap_renderer->header()}}