If you're just getting started with GWT Charts, it's possible that you'll come across a very common error: "No source code is available for type com.googlecode.gwt.charts.client.corechart.*; did you forget to inherit a required module?". This is how you can resolve it:

This error is caused by not inheriting com.googlecode.gwt.charts.Charts in your project's xml file.

Just add this line into *gwt.xml file:

  <inherits name="com.googlecode.gwt.charts.Charts"/>

Here are two screenshot to illustrate the change.

This is where you'd find a file for a hypothetical project called: MortgageCalculator:

And this is where the inherit line needs to be added:

If this helped in any way, don't hesitate to leave a comment below.