CIBA authorization request returns HTTP 500 NPE when file is wrong

Error leading customer to what is expected request payload

$ http -v -a ${USER}:${PASS} POST ${URL}/oauth2/bc-authorize
POST /openam/oauth2/bc-authorize HTTP/1.1
Accept: */*
Accept-Encoding: gzip, deflate
Authorization: Basic bXlDbGllbnRJRDpwYXNzd29yZA==
Connection: keep-alive
Content-Length: 0
Host: amqa-clone70.test.forgerock.com:8080
User-Agent: HTTPie/0.9.8

HTTP/1.1 500 
Connection: close
Content-Length: 24
Content-Type: application/json;charset=UTF-8
Date: Wed, 05 Jun 2019 09:46:41 GMT
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN

{
    "error": "server_error"
}

$ cat openam/openam/debug/OAuth2Provider 
o.f.o.r.ExceptionHandler: 2019-06-05 10:46:41,688: Thread[http-nio-8080-exec-10]: TransactionId[7eb23208-34c3-4c55-9f2a-a332659acf74-61802]
ERROR: Unhandled exception: 
java.lang.NullPointerException: null
	at org.forgerock.json.jose.common.JwtReconstruction.reconstructJwt(JwtReconstruction.java:61)
	at org.forgerock.oauth2.core.OAuth2Jwt.create(OAuth2Jwt.java:70)
	at org.forgerock.oauth2.restlet.BackChannelResource.backChannelAuthorize(BackChannelResource.java:136)
	at sun.reflect.GeneratedMethodAccessor105.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:483)
	at org.forgerock.openam.http.annotations.AnnotatedMethod.invoke(AnnotatedMethod.java:81)
	at org.forgerock.openam.http.annotations.Endpoints$1.handle(Endpoints.java:77)
	at org.forgerock.http.handler.Handlers$UndescribedAsDescribableHandler.handle(Handlers.java:179)
	at org.forgerock.openam.audit.AbstractHttpAccessAuditFilter.filter(AbstractHttpAccessAuditFilter.java:88)
	at org.forgerock.http.handler.Handlers$1.handle(Handlers.java:53)
	at org.forgerock.http.routing.Router.handle(Router.java:100)
	at org.forgerock.openam.rest.RealmContextFilter.filter(RealmContextFilter.java:85)
	at org.forgerock.http.handler.Handlers$1.handle(Handlers.java:53)
	at org.forgerock.http.routing.Router.handle(Router.java:100)
	at org.forgerock.openam.http.HttpRoute$6.handle(HttpRoute.java:206)
	at org.forgerock.http.routing.Router.handle(Router.java:100)
	at org.forgerock.openam.dpro.session.ProofOfPossessionTokenFilter.filter(ProofOfPossessionTokenFilter.java:88)
	at org.forgerock.http.handler.Handlers$1.handle(Handlers.java:53)
	at org.forgerock.http.swagger.OpenApiRequestFilter.filter(OpenApiRequestFilter.java:63)
	at org.forgerock.http.handler.Handlers$1.handle(Handlers.java:53)
	at org.forgerock.openam.http.ApiDescriptorFilter.filter(ApiDescriptorFilter.java:139)
	at org.forgerock.http.handler.Handlers$1.handle(Handlers.java:53)
	at org.forgerock.openam.http.ResponseContext$ResponseContextFilter.filter(ResponseContext.java:53)
	at org.forgerock.http.handler.Handlers$1.handle(Handlers.java:53)
	at org.forgerock.openam.http.OpenAMHttpApplication.lambda$static$1(OpenAMHttpApplication.java:60)
	at org.forgerock.openam.http.OpenAMHttpApplication$$Lambda$828/1545480468.filter(Unknown Source)
	at org.forgerock.http.handler.Handlers$1.handle(Handlers.java:53)
	at org.forgerock.openam.http.OpenAMHttpApplication.lambda$cacheHeaderFilter$3(OpenAMHttpApplication.java:88)
	at org.forgerock.openam.http.OpenAMHttpApplication$$Lambda$899/1215841189.filter(Unknown Source)
	at org.forgerock.http.handler.Handlers$1.handle(Handlers.java:53)
	at org.forgerock.http.filter.TransactionIdInboundFilter.filter(TransactionIdInboundFilter.java:86)
	at org.forgerock.http.handler.Handlers$1.handle(Handlers.java:53)
	at org.forgerock.http.servlet.HttpFrameworkServlet.service(HttpFrameworkServlet.java:265)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.forgerock.openam.validation.ResponseValidationFilter.doFilter(ResponseValidationFilter.java:59)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.forgerock.openam.headers.SetHeadersFilter.doFilter(SetHeadersFilter.java:80)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.forgerock.openam.headers.SetHeadersFilter.doFilter(SetHeadersFilter.java:80)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at com.sun.identity.setup.AMSetupFilter.doFilter(AMSetupFilter.java:115)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.forgerock.openam.audit.context.AuditContextFilter.doFilter(AuditContextFilter.java:47)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:800)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1471)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:745)