Bug 182190 [StatusHandling] [Wizards] getControl assert on wizard page has no message
M6 If you forget to set the control on your wizard page our assert gives no feedback. We need an error message.
bundles/org.eclipse.jface/src/org/eclipse/jface/wizard/WizardDialog.java
pmlayout.numColumns = 1;
        progressMonitorPart = createProgressMonitorPart(composite, pmlayout);
        GridData gridData = new GridData(GridData.FILL_HORIZONTAL);
        progressMonitorPart
                .setLayoutData(gridData);
        progressMonitorPart.setVisible(false);
        
        Label separator = new Label(composite, SWT.HORIZONTAL | SWT.SEPARATOR);
        separator.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
        applyDialogFont(progressMonitorPart);
        return composite;
    }
    /**
     * Create the progress monitor part in the receiver.
     * @param composite
     * @param pmlayout
     * @return ProgressMonitorPart
     */
    protected ProgressMonitorPart createProgressMonitorPart(
            Composite composite, GridLayout pmlayout) {
        return new ProgressMonitorPart(composite, pmlayout, SWT.DEFAULT) {
            String currentTask = null;
            /* (non-Javadoc)
             * @see org.eclipse.jface.wizard.ProgressMonitorPart#setBlocked(org.eclipse.core.runtime.IStatus)
             */
            public void setBlocked(IStatus reason) {
                super.setBlocked(reason);
                if (!lockedUI) {
					getBlockedHandler().showBlocked(getShell(), this, reason,
                            currentTask);