A click step might throw ArgumentNullException when executed against a pop up that is in the process of being opened.

Details:

Exception 'System.ArgumentNullException: Value cannot be null.

Parameter name: source
   at System.Linq.Enumerable.Where[TSource](IEnumerable`1 source, Func`2 predicate)
   at ArtOfTest.WebAii.DesktopAutomation.DesktopFind.GatherResultsFromXPathSearch(String xPath, Int32 maxDepth, DesktopFindExpressionGroup group, List`1 roots, List`1 results)
   at ArtOfTest.WebAii.DesktopAutomation.DesktopFind.<>c__DisplayClass26_0.<AllByExpression>b__0()
   at ArtOfTest.WebAii.DesktopAutomation.DesktopFind.RetryIfNullOrEmpty[T](Int32 retries, Int32 retryDelay, Func`1 findFunc)
   at ArtOfTest.WebAii.DesktopAutomation.DesktopFind.AllByExpression(DesktopFindExpression expression, Int32 maxDepth, Int32 maxRetries, Int32 retryDelay)
   at ArtOfTest.WebAii.Design.Execution.ExecutionUtils.FindElementInternal(IAutomationHost targetHost, FindExpressionElement expression, Region region, String& error)
   at ArtOfTest.WebAii.Design.Execution.ExecutionUtils.FindTargets(IAutomationHost targetHost, AutomationDescriptor baseDescriptor)