Missing context is creating warnings

[alexdamsted]

Missing context from pluginfile.php is creating set_context warnings.

E.g.,

PHP message: Debugging: Coding problem: $PAGE->context was not set. You may have forgotten to call require_login() or $PAGE->set_context(). The page may not display correctly as a result in #12*
line 572 of /lib/pagelib.php: call to debugging()#12*
line 1730 of /lib/pagelib.php: call to moodle_page->magic_get_context()#12*
line 239 of /theme/snap/config.php: call to moodle_page->initialise_theme_and_output()#12*
line 2362 of /lib/outputlib.php: call to include()#12*
line 710 of /lib/outputlib.php: call to theme_config::find_theme_config()#12*
line 229 of /theme/snap/lib.php: call to theme_config::load()#12* line 5316 of /lib/filelib.php: call to theme_snap_pluginfile()#12*
line 44 of /pluginfile.php: call to file_pluginfile()" while reading response header from upstream