Fix crash if LD input contact isn't connected

Traceback (most recent call last):
File "/home/developer/WorkData/PLC/beremiz/beremiz/BeremizIDE.py", line 339, in OnMethod
obj.CTR.CallMethod('_'+meth)
File "/home/developer/WorkData/PLC/beremiz/beremiz/ProjectController.py", line 1996, in CallMethod
getattr(self, method)()
File "/home/developer/WorkData/PLC/beremiz/beremiz/ProjectController.py", line 1134, in _Build
IECGenRes = self._Generate_SoftPLC()
File "/home/developer/WorkData/PLC/beremiz/beremiz/ProjectController.py", line 746, in _Generate_SoftPLC
if self._Generate_PLC_ST():
File "/home/developer/WorkData/PLC/beremiz/beremiz/ProjectController.py", line 763, in _Generate_PLC_ST
self._getIECgeneratedcodepath())
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCControler.py", line 456, in GenerateProgram
self.ProgramChunks = GenerateCurrentProgram(self, self.Project, errors, warnings)
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 1762, in GenerateCurrentProgram
generator.GenerateProgram()
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 478, in GenerateProgram
self.GeneratePouProgram(pou_name)
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 260, in GeneratePouProgram
program = pou_program.GenerateProgram(pou)
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 1718, in GenerateProgram
self.ComputeProgram(pou)
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 1028, in ComputeProgram
self.GenerateBlock(instance, block_infos, body, None)
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 1144, in GenerateBlock
expression = self.ComputeExpression(body, connections, executionOrderId > 0)
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 1373, in ComputeExpression
paths = self.GeneratePaths(connections, body, order, to_inout)
File "/home/developer/WorkData/PLC/beremiz/beremiz/PLCGenerator.py", line 1344, in GeneratePaths
elif isinstance(result[0], list):
IndexError: list index out of range


Close #70

// import Nevow.Athena
// import Divmod.Base

function updateAttr(id, param, value) {
  Nevow.Athena.Widget.fromAthenaID(1).callRemote('HMIexec', 'setattr', id, param, value);
}

var svguiWidgets = new Array();

var currentObject = null;
function setCurrentObject(obj) {
	currentObject = obj;
}
function isCurrentObject(obj) {
	return currentObject == obj;
}

function getSVGElementById(id) {
	return document.getElementById(id);
}

function blockSVGElementDrag(element) {
	element.addEventListener("draggesture", function(event){event.stopPropagation()}, true);
}

LiveSVGPage.LiveSVGWidget = Nevow.Athena.Widget.subclass('LiveSVGPage.LiveSVGWidget');
LiveSVGPage.LiveSVGWidget.methods(

    function handleEvent(self, evt) {
        if (currentObject != null) {
            currentObject.handleEvent(evt);
        }
    },

    function receiveData(self, data){
        dataReceived = json_parse(data);
        gadget = svguiWidgets[dataReceived.id]
        if (gadget) {
        	gadget.updateValues(json_parse(dataReceived.kwargs));
        }
        //console.log("OBJET : " + dataReceived.back_id + " STATE : " + newState);
    },
    
    function init(self, arg1){
        //console.log("Object received : " + arg1);
        for (ind in arg1) {
            gad = json_parse(arg1[ind]);
            args = json_parse(gad.kwargs);
            gadget = new svguilib[gad.__class__](self, gad.id, args);
            svguiWidgets[gadget.id]=gadget;
            //console.log('GADGET :' + gadget);
        }
        var elements = document.getElementsByTagName("svg");
        for (var i = 0; i < elements.length; i++) {
        	elements[i].addEventListener("mouseup", self, false);
        }
        //console.log("SVGUIWIDGETS : " + svguiWidgets);
    }
);