Site Content and Structure is broken.. or is it ?

You may run occasionally into this, so I thought this post could save you some long troubleshooting steps.
the scenario is simple: you want to visit the Content and Structure page and receive an unexpected error.
Looking at the ULS Logs you see the following Exception:

System.ArgumentException: Invalid value. The value cannot be an empty string. Parameter name: stringId
at Microsoft.SharePoint.Publishing.CommonUtilities.ConfirmNotNullOrEmptyString(String value, String parameterName)
at Microsoft.SharePoint.Publishing.Internal.WebControls.ToolbarViewSelectionDropdown.AddMenuItem(String itemId, ListItem itemTitleDesc, String itemOnClickScript, Boolean checkMenuItem)
at Microsoft.SharePoint.Publishing.Internal.WebControls.ToolbarViewSelectionDropdown.CreateChildControls()
at System.Web.UI.Control.EnsureChildControls()
at Microsoft.SharePoint.Publishing.Internal.WebControls.ToolbarViewSelectionDropdown.OnLoad(EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Control.AddedControl(Control control, Int32 index)
at Microsoft.SharePoint.Publishing.Internal.WebControls.Toolbar.Add(ToolbarObject objItem)

You can deduct based on the call stack that something is wrong with the toolbar and we have some strings that are empty. But which ones ?
The answer is simple: The Views dropdown on top of the list/web on the right side is built based on the content YOU can create in the Content and Structure Reports List

the mandatory fields in that list are Title and Description, so if you by mistake forgot to fill in the title or the description, you will run into this.
Solution ?

Look in the Content and Structure Reports List for empty valued title and description and fill in the missing values.