Wrong error message shown

When a signature is required for a AuthnRequest (for example, if the ACSlocation in the request is not registered in SR), and the signature verification fails (or the request is unsigned), Engineblock shows the wrong error message: "Error - Invalid Identity Provider response".

The EB log shows, otoh:

EngineBlock_Corto_Module_Bindings_VerificationException: Validation of received messages enabled, but no signature found on message.
#0 /opt/openconext/OpenConext-engineblock-5.4.0/library/EngineBlock/Corto/Adapter.php(137): EngineBlock_Corto_Module_Bindings->receiveRequest()
#1 /opt/openconext/OpenConext-engineblock-5.4.0/library/EngineBlock/Corto/Adapter.php(304): EngineBlock_Corto_Adapter->_getRequestInstance()
#2 /opt/openconext/OpenConext-engineblock-5.4.0/library/EngineBlock/Corto/Adapter.php(154): EngineBlock_Corto_Adapter->_getIssuerSpEntityId()
#3 /opt/openconext/OpenConext-engineblock-5.4.0/library/EngineBlock/Corto/Adapter.php(42): EngineBlock_Corto_Adapter->_filterRemoteEntitiesByRequestSp()
#4 /opt/openconext/OpenConext-engineblock-5.4.0/src/OpenConext/EngineBlockBundle/Controller/IdentityProviderController.php(94): EngineBlock_Corto_Adapter->singleSignOn(NULL)
#5 [internal function]: OpenConext\EngineBlockBundle\Controller\IdentityProviderController->singleSignOnAction(NULL, NULL)
#6 /opt/openconext/OpenConext-engineblock-5.4.0/app/bootstrap.php.cache(3222): call_user_func_array(Array, Array)
#7 /opt/openconext/OpenConext-engineblock-5.4.0/app/bootstrap.php.cache(3181): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
#8 /opt/openconext/OpenConext-engineblock-5.4.0/app/bootstrap.php.cache(3335): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#9 /opt/openconext/OpenConext-engineblock-5.4.0/app/bootstrap.php.cache(2540): Symfony\Component\HttpKernel\DependencyInjection\ContainerAwareHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#10 /opt/openconext/OpenConext-engineblock-5.4.0/web/app.php(22): Symfony\Component\HttpKernel\Kernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#11 {main}

Start with the exception path in library/EngineBlock/Corto/Adapter.php and the request handling entry point in src/OpenConext/EngineBlockBundle/Controller/IdentityProviderController.php. Reproduce an unsigned or failed-signature AuthnRequest and trace how the VerificationException becomes the displayed error. Done means these cases no longer show “Invalid Identity Provider response” and instead present the appropriate verification failure.