Deleting Font-level and Glyph-level guides at the same time produces a traceback

[colinmford]

I am getting a traceback when deleting font-level and glyph-level guides together. Tool still allows me to delete them separately, so this is pretty minor.

Reproduce:

1. Drag in a glyph-level guide from edge
2. Hold cmd, drag in a font-level guide from edge
3. Select both and hit delete key

Traceback:

  File "/Users/colinmford/Library/Application Support/RoboFont/plugins/Guide Tool.roboFontExt/lib/guideTool/tool.py", line 555, in keyDown
AttributeError: 'NoneType' object has no attribute 'undo'

The Line 555 in question.

Possibly related to #8 ?

[typesupply]

This should be fixed. Thanks!

[colinmford]

LGTM!