Exception when opening screen from the login screen

[glebfox]

Environment

• Platform version: 7.2.0

Description of the bug or enhancement

• Minimal reproducible example

https://github.com/cuba-platform/sample-user-registration

1. Update project to 7.2
2. Start the app
3. On the login screen click either Register or Restore password

• Actual behavior

...
Caused by: java.lang.NullPointerException: null
	at com.haulmont.cuba.web.sys.WebUrlRouting.getStateMark(WebUrlRouting.java:337) ~[cuba-web-7.2.0.jar:7.2.0]
	at com.haulmont.cuba.web.sys.WebUrlRouting.buildNavState(WebUrlRouting.java:160) ~[cuba-web-7.2.0.jar:7.2.0]
	at com.haulmont.cuba.web.sys.WebUrlRouting.updateState(WebUrlRouting.java:129) ~[cuba-web-7.2.0.jar:7.2.0]
	at com.haulmont.cuba.web.sys.WebUrlRouting.pushState(WebUrlRouting.java:95) ~[cuba-web-7.2.0.jar:7.2.0]
	at com.haulmont.cuba.web.sys.WebScreens.changeUrl(WebScreens.java:555) ~[cuba-web-7.2.0.jar:7.2.0]
	at com.haulmont.cuba.web.sys.WebScreens.show(WebScreens.java:470) ~[cuba-web-7.2.0.jar:7.2.0]
	at com.haulmont.cuba.gui.screen.Screen.show(Screen.java:309) ~[cuba-gui-7.2.0.jar:7.2.0]
	at com.company.sample.web.screens.loginscreen.ExtLoginScreen.onRegisterBtnClick(ExtLoginScreen.java:45) ~[app-web-0.1-SNAPSHOT.jar:na]
...

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Caused by: #2258