Elasticsearch: Fix crash with invalid performance data metrics

fixes #6191

refs #6192

lib/perfdata/elasticsearchwriter.cpp

@@ -148,6 +148,7 @@ void ElasticsearchWriter::AddCheckResult(const Dictionary::Ptr& fields, const Ch
 					Log(LogWarning, "ElasticsearchWriter")
 					    << "Ignoring invalid perfdata value: '" << val << "' for object '"
 					    << checkable->GetName() << "'.";
+					continue;
 				}
 			}