Check your configuration file (F:\Program Files (x86)\Tridion\customizations\HelloWorld\config\HelloWorld.config) for unclosed tags or some typo.
To create button in context menu:
Check that your HelloWorld.config extends contextmenu node
<ext:contextmenus>
<ext:add>
<ext:extension name="Hello World" assignid="" insertbefore="cm_preview">
<ext:menudeclaration>
<cmenu:ContextMenuItem id="HelloWorld" name="Hello World" command="HelloWorld"/>
</ext:menudeclaration>
<ext:dependencies>
<cfg:dependency>RandomStringThatNeedsToBeCompiled2</cfg:dependency>
</ext:dependencies>
<ext:apply>
<ext:view name="DashboardView"/>
</ext:apply>
</ext:extension>
</ext:add>
</ext:contextmenus>
Modify your helloworld.js to enable button only for Components
Common.Tridion.MVP.HelloWorld.prototype.isAvailable = function HelloWorld$isAvailable(selection)
{
var itemID = selection.getItem(0);
if ($models.getItemType(itemID) != $const.ItemType.COMPONENT) {
return false;
}
};
Don't forget to clear your cache