Traceback (most recent call last):
  File "/Applications/RoboFont.app/Contents/Resources/lib/python2.7/vanilla/dialogs.py", line 110, in savePanelDidEnd_returnCode_contextInfo_
    self._resultCallback(self._result)
  File "lib/doodleFontWindow.pyc", line 318, in _compileFont
  File "lib/fontObjects/doodleFont.pyc", line 677, in generate
  File "lib/fontObjects/doodleFont.pyc", line 769, in prepareCompile
  File "lib/fontObjects/doodleFont.pyc", line 784, in compileRemoveOverlap
  File "lib/fontObjects/doodleContour.pyc", line 34, in join
IndexError: list index out of range
Traceback (most recent call last):
  File "lib/doodleDelegate.pyc", line 65, in sendEvent_
  File "/Applications/RoboFont.app/Contents/Resources/lib/python2.7/vanilla/dialogs.py", line 110, in savePanelDidEnd_returnCode_contextInfo_
    self._resultCallback(self._result)
  File "lib/doodleFontWindow.pyc", line 318, in _compileFont
  File "lib/fontObjects/doodleFont.pyc", line 677, in generate
  File "lib/fontObjects/doodleFont.pyc", line 769, in prepareCompile
  File "lib/fontObjects/doodleFont.pyc", line 784, in compileRemoveOverlap
  File "lib/fontObjects/doodleContour.pyc", line 34, in join
IndexError: list index out of range

Generating in Area51 works, but gives me this error:

makeotfexe [WARNING]  [internal] Feature block seen before any language system statement.  You should place languagesystem statements before any feature definition [features 1]
makeotfexe [WARNING]  Vendor name too short. Padded automatically to 4 characters. [features 1161]
makeotfexe [WARNING]  Major version number not in range 1 .. 255 [features 1165]

Any ideas how to resolve this?

Try running this script looking for open contours and remove them instead of trying to close them, or send me the UFO.

f = CurrentFont()

for g in f:
    contoursToRemove = []
    for c in g:
        if c.open:
            ## collect all open contours
            contoursToRemove.append(c)
    
    for c in contoursToRemove:
        ## remove all open contours
        g.removeContour(c)
    
    if contoursToRemove:
        g.update()