[Script] Problem with changing colors using selection and doc.defaultFillColor

OK, I have worked up a complete test suite. I am getting the layer error on this simple document that I have attached. 
 

var CMTest = {
     makeColor : function(cmyk, key) {
        //lm.writeln(3, "Entering makeColor");
        var c = new CMYKColor();
            c.cyan = Number(cmyk.c);
            c.magenta = Number(cmyk.m);
            c.yellow = Number(cmyk.y);
            c.black = Number(cmyk.k);
            c.name = key;
        return c;
    },

    /**
     * @description Validates that any colors in data are valid hex values. Alerts user of any invalid colors.
     * @returns {Boolean} true if all colors in data are valid hex values, false if not. Alerts user of any invalid colors.
     */
    isValidColor : function(val) {

        var rx = /^[0-9a-f]{6}$/i;
        var p = undefined;
        c = val.replace(/#/, "");
        if (c && !rx.test(c)) {
            //lm.writeln(1, "Color " + c + " is not a valid hex color. Skipping color changing.");
            return false;
        }
        return true;
    },
    /**
     * @description Converts a hex color string to an RGB array.
     * @param {String} hex A hex color string, with or without a leading #.
     * @returns {Array} An array of three integers representing the RGB values of the color.
     */
    hexToRGB : function(hex) {
        var c = hex.replace(/#/, "");
        return [parseInt(c.substr(0,2), 16), parseInt(c.substr(2,2), 16), parseInt(c.substr(4,2), 16)];
    },

    /**
     * 
     * @param {Integer} r 
     * @param {Integer} g 
     * @param {Integer} b 
     * @returns {Object} An object with properties c, m, y, and k representing the cyan, magenta, yellow, and black values of the color as percentages.
     */
    rgbToCmyk : function(r, g, b) {
        // Normalize RGB values to 0-1
        var r_norm = r / 255;
        var g_norm = g / 255;
        var b_norm = b / 255;

        // Calculate Black (K)
        var k = 1 - Math.max(r_norm, g_norm, b_norm);

        // If the color is pure black
        if (k === 1) {
            return { c: 0, m: 0, y: 0, k: 100 };
        }

        // Calculate Cyan, Magenta, and Yellow
        var c = (1 - r_norm - k) / (1 - k);
        var m = (1 - g_norm - k) / (1 - k);
        var y = (1 - b_norm - k) / (1 - k);

        // Return as percentages rounded to nearest integer
        return {
            c: Math.round(c * 100),
            m: Math.round(m * 100),
            y: Math.round(y * 100),
            k: Math.round(k * 100)
        };
    },
    /**
     * @description 
     * @param {Document} doc 
     */
    changeColor : function(doc, data) {
        //lm.writeln(3, "Entering changeColor");
        var p, c, rgb, cmyk, swatch, layer, pi = undefined;
        var crx = /color/i;
        var oldDefaultColor = doc.defaultFillColor;

        for (p in data) {
            c = data[p];
            p = p.toUpperCase();
            alert(p);
            if (crx.test(p) && c) {
                alert(c);
                if (this.isValidColor(c)) {
                    alert("is valid");
                    try {
                        layer = doc.layers.getByName(p);
                    } catch(e) {
                        alert("Error getting layer: " + e);
                        continue;
                    }
                    if (!layer.pageItems.length) {
                        //lm.writeln(2, "No page items in layer " + p + " to change color on."); 
                        continue; 
                    } 
                    rgb = this.hexToRGB(c);
                    cmyk = this.rgbToCmyk(rgb[0], rgb[1], rgb[2]);
                    swatch = this.makeColor(cmyk, p);
                    layer.hasSelectedArtwork = true;
                    //lm.writeln(4, "Do I have a page item selected: " + doc.selection.length);
                    //app.executeMenuCommand("Find Fill Color menu item");
                    //lm.writeln(4, "Do I have a doc still after app fill: " + doc.name);
                    doc.defaultFillColor = swatch;
                    doc.selection = null;
                    //lm.writeln(4, "Do I have a doc still after default color: " + doc.name);
                    //Utils.deselectItems(doc.selection);
                    //lm.writeln(4, "Do I still have a doc after deselecting: " + doc.name);

                }
            }
        }
        try {
            doc.defaultFillColor = oldDefaultColor;
        } catch(e) {
            alert("Is this the bug with color change?");
        }
    }

}

CMTest.changeColor(app.activeDocument, { backgroundColor: "111111", overlayColor: "222222", color2: "333333"});