code: function toggleCollapsed(collapsed, doNotSave) {
          if (collapsed === undefined) {
              collapsed = !_collapsed;
          }
  
          if (collapsed === _collapsed) {
              return;
          }
  
          _collapsed = collapsed;
          if (!doNotSave) {
              prefs.set(PREF_COLLAPSED, _collapsed);
              prefs.save();
          }
  
          if (_collapsed) {
              Resizer.hide($problemsPanel);
          } else {
              if (_hasErrors) {
                  Resizer.show($problemsPanel);
              }
          }
      }
docs: Toggle the collapsed state for the panel. This explicitly collapses the panel (as opposed to
  the auto collapse due to files with no errors & filetypes with no provider). When explicitly
  collapsed, the panel will not reopen automatically on switch files or save.
  
  @param {?boolean} collapsed Collapsed state. If omitted, the state is toggled.
  @param {?boolean} doNotSave true if the preference should not be saved to user settings. This is generally for events triggered by project-level settings.