Performance: simplifed checking for reserved label keyword (#705)

Author: Connormiha

lib/summary.js

@@ -18,6 +18,9 @@ class Summary extends Metric {
 			store: new LabelMap(),
 		});
 
+		if (this.labelNames.includes('quantile'))
+			throw new Error('quantile is a reserved label keyword');
+
 		this.type = 'summary';
 		this.store = new LabelMap(this.labelNames);
 
@@ -31,10 +34,6 @@ class Summary extends Metric {
 				},
 			);
 		}
-		for (const label of this.labelNames) {
-			if (label === 'quantile')
-				throw new Error('quantile is a reserved label keyword');
-		}
 	}
 
 	/**