@Override
	protected void programClosed(Program program) {
		program.removeListener(this);

		// Find any providers showing scalars for the closed program and
		// eliminate them.
		Iterator<ScalarSearchProvider> iter = providers.iterator();
		while (iter.hasNext()) {
			ScalarSearchProvider provider = iter.next();
			if (provider.getProgram() == program) {
				provider.programClosed(program);
				iter.remove();
			}
		}
	}
We need to be aware of changes to the program that could result in scalars being
added/removed. When this happens we want to update the appropriate providers.

@param ev the domain change event
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/scalartable/ScalarSearchPlugin.java