On the File Status tab of a Git repository, I select multiple files and then pressed space, in the hope to try add multiple files to the staging area in one go, which successed but SourceTree also crashed. The following was all that was related to the crash in the log file.

2015-07-15T12:30:59: Fatal error:
System.NullReferenceException: Object reference not set to an instance of an object.

2015-07-15T12:30:59: Stack trace:
at System.Windows.Controls.SelectionMultiple.SelectCurrentBySpace() in C:\projects\bitbucket.org\atlassian\sourcetreewin\Dependencies\MultiSelectTreeView\Controls\SelectionMultiple.cs:line 223
at System.Windows.Controls.MultiSelectTreeViewItem.OnKeyDown(KeyEventArgs e) in C:\projects\bitbucket.org\atlassian\sourcetreewin\Dependencies\MultiSelectTreeView\Controls\MultiSelectTreeViewItem.cs:line 687
at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
at System.Windows.Input.InputManager.ProcessStagingArea()
at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
at System.Windows.Interop.HwndKeyboardInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawKeyboardActions actions, Int32 scanCode, Boolean isExtendedKey, Boolean isSystemKey, Int32 virtualKey)
at System.Windows.Interop.HwndKeyboardInputProvider.ProcessKeyAction(MSG& msg, Boolean& handled)
at System.Windows.Interop.HwndSource.CriticalTranslateAccelerator(MSG& msg, ModifierKeys modifiers)
at System.Windows.Interop.HwndSource.OnPreprocessMessage(Object param)
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)