MDL-58843 core: Do not expect a particular class of the thrown exception

Since PHP 7, the custom exception handlers are also called to handle
thrown Errors which are not Exceptions.

mod/lti/classes/service_exception_handler.php

@@ -94,9 +94,9 @@ class service_exception_handler {
     /**
      * Echo an exception message encapsulated in XML.
      *
-     * @param \Exception $exception The exception that was thrown
+     * @param \Exception|\Throwable $exception The exception that was thrown
      */
-    public function handle(\Exception $exception) {
+    public function handle($exception) {
         $message = $exception->getMessage();
 
         // Add the exception backtrace for developers.

webservice/xmlrpc/locallib.php

@@ -161,11 +161,11 @@ class webservice_xmlrpc_server extends webservice_base_server {
     /**
      * Generate the XML-RPC fault response.
      *
-     * @param Exception $ex The exception.
+     * @param Exception|Throwable $ex The exception.
      * @param int $faultcode The faultCode to be included in the fault response
      * @return string The XML-RPC fault response xml containing the faultCode and faultString.
      */
-    protected function generate_error(Exception $ex, $faultcode = 404) {
+    protected function generate_error($ex, $faultcode = 404) {
         $error = $ex->getMessage();
 
         if (!empty($ex->errorcode)) {