Bug 131516 [Browser] NullPointerException in MozillaBrowser.openURL()
In MozillaBrowser.openURL() there is no check to see if the argument url2 is null before calling url2.toExternalForm(). So passing in null to this method results in a NullPointerException.
bundles/org.eclipse.ui.browser/src/org/eclipse/ui/internal/browser/browsers/MozillaBrowser.java
waitForBrowser();
			if (exitRequested)
				return;
			if (firstLaunch && Platform.OS_WIN32.equals(Platform.getOS())) {
				if (openBrowser(executable + " " + url) == 0) 
					return;
				browserFullyOpenedAt = System.currentTimeMillis() + DELAY;
				return;
			}
			if (openBrowser(executable + " -remote openURL(" + url + ")") 
					== 0)
				return;
			
			if (exitRequested)
				return;
			browserFullyOpenedAt = System.currentTimeMillis() + DELAY;
			openBrowser(executable + " " + url); 
		}
		private void waitForBrowser() {
			while (System.currentTimeMillis() < browserFullyOpenedAt)
				try {
					if (exitRequested)
						return;
					Thread.sleep(100);
				} catch (InterruptedException ie) {
					
				}
		}
	}
}