ODataUrlValidator.ValidateProperties null reference exception on dynamic properties

[albuckle]

ODL returns a NullReferenceException when validating URLs with dynamic properties for deprecation.

Sample repro uri: graph.microsoft.com/v1.0/drives('<key>')/items('<key>')/<dynamic>

Stack trace:
at Microsoft.OData.UriParser.Validation.ODataUrlValidator.ValidateProperties(IEdmType edmType, ODataUrlValidationContext context) in D:\a\1\s\src\Microsoft.OData.Core\UrlValidation\ValidationEngine\ODataUrlValidator.cs:line 444
at Microsoft.OData.UriParser.Validation.ODataUrlValidator.ValidateSelectExpandClause(IEdmType segmentType, SelectExpandClause selectExpand, ODataUrlValidationContext validationContext) in D:\a\1\s\src\Microsoft.OData.Core\UrlValidation\ValidationEngine\ODataUrlValidator.cs:line 249
at Microsoft.OData.UriParser.Validation.ODataUrlValidator.ValidateUrl(ODataUri odataUri, IEnumerable`1& validationMessages) in D:\a\1\s\src\Microsoft.OData.Core\UrlValidation\ValidationEngine\ODataUrlValidator.cs:line 66