Fix issue when can not load broken PIO Core state

HISTORY.rst

@@ -4,6 +4,11 @@ Release Notes
 PlatformIO 3.0
 --------------
 
+3.4.1 (2017-??-??)
+~~~~~~~~~~~~~~~~~~
+
+* Fixed issue when can not load broken PIO Core state
+
 3.4.0 (2017-06-26)
 ~~~~~~~~~~~~~~~~~~
 

platformio/app.py

@@ -88,7 +88,7 @@ class State(object):
             self._lock_state_file()
             if isfile(self.path):
                 self._state = util.load_json(self.path)
-        except ValueError:
+        except exception.PlatformioException:
             self._state = {}
         self._prev_state = deepcopy(self._state)
         return self._state