Error if keymap file has bindings to disabled package #9

If *.sublime-keymap has binding to disabled package then package doesn't work.

For example
{ "keys": ["ctrl+alt+{"], "command": "move_to", "args": {"to": "{", "extend": false} }

Sublime console write:
Unable to parse binding {key: following_text, keys: [ctrl+alt+{], match_all: false, operand: , operator: regex_contains}

Now pressing shift+f10 the console write:
Traceback (most recent call last): File "./sublime_plugin.py", line 362, in run_ File "./boundkeys.py", line 373, in run File "./boundkeys.py", line 93, in getOutput KeyError: 'command'