Deleting a SAML2 entity that is not assigned to a COT succeeds but logs an NPE

Description:

Deleting a SAML entity that is not assigned to a COT succeeds, but results in an NPE being logged at error level to the Federation log.

Reproduction steps:

1. Deploy AM, embedded config and user store.
2. Login as amadmin. Navigate to top level realm, Applications and then Federation.
3. Create a hosted entity, and provide an alias, e.g. idp alias of idp (/idp).
4. View the list of entities under the Applications, Federation.
5. Delete the created entity.
6. View the list of entities again.

Expected behaviour:

Entity has been deleted and no error information has been logged.

Current behaviour:

Entity has been deleted but the following NPE is logged in Federation log:

ERROR: SAML2MetaManager.removeFromCircleOfTrust: Error while removing entity https://openam.amtest2.com:8443/access;v1.1 from COT.
java.lang.NullPointerException: null
[CONTINUED]     at com.sun.identity.saml2.meta.SAML2MetaManager.removeFromCircleOfTrust(SAML2MetaManager.java:1207)
[CONTINUED]     at com.sun.identity.saml2.meta.SAML2MetaManager.deleteEntityDescriptor(SAML2MetaManager.java:709)
[CONTINUED]     at org.forgerock.openam.federation.rest.Saml2EntitiesCollectionProvider.delete(Saml2EntitiesCollectionProvider.java:132)
[CONTINUED]     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)