How to remove all the spaces from a text frame?

There is a text frame in a document. Whete each world is colored by a seprate color. 
I try to remove all the spaces in the frame but there is an error "No such element"

 on the line "var wordRange = textFrame.textRange.characters[charIndex];"

var doc = app.activeDocument;
var textFrame = doc.textFrames[0]; // assume text frame is present

var contents = textFrame.contents;
var words = contents.split(" ");
var colors = [];

var charIndex = 0;
for (var i = 0; i < words.length; i++) {
    var wordLength = words[i].length;
    var wordRange = textFrame.textRange.characters[charIndex];
    wordRange.length = wordLength;
    colors.push(wordRange.fillColor);
    charIndex += wordLength + 1;
}

var newContents = contents.replace(/\s+/g, '');

var newTextFrame = doc.textFrames.add();
newTextFrame.position = textFrame.position;
newTextFrame.contents = newContents;

charIndex = 0;
for (var i = 0; i < words.length; i++) {
    var wordLength = words[i].length;
    var textRange = newTextFrame.textRange.characters[charIndex];
    textRange.length = wordLength;
    textRange.fillColor = colors[i];
    charIndex += wordLength;
}

How to fix it?