Check if we have all scheme mangers on new session

messages.go

@@ -103,6 +103,8 @@ const (
 	ErrorUnknownCredentialType = ErrorType("unknownCredentialType")
 	// Error during downloading of credential type, issuer, or public keys
 	ErrorConfigurationStoreDownload = ErrorType("configurationStoreDownload")
+	// IRMA requests refers to unknown scheme manager
+	ErrorUnknownSchemeManager = ErrorType("unknownSchemeManager")
 )
 
 func (e *SessionError) Error() string {

session.go

@@ -187,7 +187,12 @@ func (session *session) start() {
 
 	// Check if we are registered to all involved keyshare servers
 	for id := range session.irmaSession.Identifiers().SchemeManagers {
-		distributed := session.credManager.ConfigurationStore.SchemeManagers[id].Distributed()
+		manager, ok := session.credManager.ConfigurationStore.SchemeManagers[id]
+		if !ok {
+			session.fail(&SessionError{ErrorType: ErrorUnknownSchemeManager, Info: id.String()})
+			return
+		}
+		distributed := manager.Distributed()
 		_, registered := session.credManager.keyshareServers[id]
 		if distributed && !registered {
 			session.transport.Delete()