Without this change, when trying to register a new WebAuthn device, the
following error appears:
2023-07-14 20:53:41,831 ERROR [freemarker.runtime] (executor-thread-5) Error executing FreeMarker template: freemarker.core.InvalidReferenceException: The following has evaluated to null or missing:
==> properties.kcWebAuthnKeyIcon [in template "webauthn-register.ftl" at line 6, column 24]