ISAICP-9456: Improve error logging.

web/modules/custom/sparql_endpoint/src/CachedSparqlReadOnlyEndpoint.php

@@ -6,6 +6,7 @@
 
 use Drupal\Component\Datetime\TimeInterface;
 use Drupal\Core\Cache\CacheBackendInterface;
+use GuzzleHttp\Exception\RequestException;
 
 /**
  * Represents a cached SPARQL read-only endpoint.
@@ -59,10 +60,18 @@ protected function getSparqlResponse(string $query, ?string $accept = NULL): Spa
     try {
       $endpointResponse = $this->sparqlReadOnlyEndpoint->query($query, $accept);
     }
+    catch (RequestException $e) {
+      return new SparqlResponse(
+        $e->getCode(),
+        $e->getResponse() ? $e->getResponse()
+          ->getBody()
+          ->getContents() : 'No response available'
+      );
+    }
     catch (\Exception $e) {
       return new SparqlResponse(
         $e->getCode(),
-        $e->getResponse()->getBody()->getContents()
+        'Error: ' . $e->getMessage()
       );
     }