Running appbuilder simulate fails if the index is not known

[gravitylow]

This seems to be an issue as of upgrading to v3.2.0 today.

If appbuilder simulate is run and the index file is not know, the simulator will open with a white screen and no option to select the index file. Previously, a dialog would appear that asks you to browse and select the index file before the simulator would open.

Let me know if you need any more details.