JS :Object is Invalid

Question

Hi all
I want to insert footnote at the end of text.
When i run my java script give error object is invalid at line no 7.
#target indesign
var myDocument = app.documents.add();
var myTextFrame = myDocument.pages.item(0).textFrames.add();
myTextFrame.geometricBounds = ["6p", "25p", "30p", "30p"];
myTextFrame.contents = "Indesign";
var word  =myTextFrame.parentStory.words.item(1);
var insertionPoint=word.insertionPoints.item(-1);    // give error  at this line Object is invalid
var footnote=insertionPoint.footnotes.item(1).add(at(1701733408));
footnote.setContents("FirstFootnote");
myDocument.FootnoteOptions.setEosPlacement(1);
Thanks.

Answer 1

Thanks Jump_Over for reply
There is another problem in my Script in the selection of Image place in textframe. I am not understand this problem also. It give error  Undefined is not an object   in 5th line.
myTextFrame = myDocument.pages.item(1).textFrames.add();
myTextFrame.geometricBounds = ["20p", "25p", "30p", "35p"];
myTextFrame.place(File("/C/version.jpg"));
var graphic=myTextFrame.allGraphics.firstItem;
graphic.select("SelectionOptions.REPLACE_WITH");  // give error Undefined is not an object
graphic.geometricBounds = ["20p", "25p", "30p", "35p"];
if I use this line
var graphic=myTextFrame.allGraphics.item(1).select("SelectionOptions.REPLACE_WITH");
then it give error
myTextFrame.allGraphics.item is not a function
Thanks.