2018-02-24 Waterfox 56.0.4_4 Edit, Preferences

TypeError: browser is undefined[Learn More]  browser.js:8138:1
	switchIfURIInWindow chrome://browser/content/browser.js:8138:1
	switchToTabHavingURI chrome://browser/content/browser.js:8166:9
	openPreferences chrome://browser/content/utilityOverlay.js:789:16
	oncommand chrome://browser/content/browser.xul:1:1