PanelIT.addPanelWithSpacesAndSymbolsInName is flickering

java.lang.IllegalArgumentException: The executed javascript does not return a boolean value
	at org.xwiki.test.ui.XWikiWebDriver.lambda$waitUntilJavascriptCondition$8(XWikiWebDriver.java:605)
	at org.openqa.selenium.support.ui.FluentWait.until(FluentWait.java:249)
	at org.xwiki.test.ui.XWikiWebDriver.waitUntilCondition(XWikiWebDriver.java:226)
	at org.xwiki.test.ui.XWikiWebDriver.waitUntilJavascriptCondition(XWikiWebDriver.java:597)
	at org.xwiki.test.ui.po.InlinePage.waitUntilPageJSIsLoaded(InlinePage.java:203)
	at org.xwiki.test.ui.po.BasePage.<init>(BasePage.java:125)
	at org.xwiki.test.ui.po.ViewPage.<init>(ViewPage.java:41)
	at org.xwiki.test.ui.po.InlinePage.<init>(InlinePage.java:32)
	at org.xwiki.panels.test.po.PanelEditPage.<init>(PanelEditPage.java:32)
	at org.xwiki.panels.test.po.PanelsHomePage.createPanel(PanelsHomePage.java:71)
	at org.xwiki.panels.test.ui.docker.PanelIT.addPanelWithSpacesAndSymbolsInName(PanelIT.java:101)