oh, also it's actually a set

Author: KTibow

lib/ExportsFieldPlugin.js

@@ -114,13 +114,14 @@ module.exports = class ExportsFieldPlugin {
 				}
 
 				if (paths.length === 0) {
-          const conditions =
-            this.conditionNames.length === 1
-              ? `the condition "${this.conditionNames[0]}"`
-              : `the conditions ${JSON.stringify(this.conditionNames)}`;
+					const conditions = [...this.conditionNames];
+          const conditionsStr =
+            conditions.length === 1
+              ? `the condition "${conditions[0]}"`
+              : `the conditions ${JSON.stringify(conditions)}`;
 					return callback(
 						new Error(
-							`"${remainingRequest}" is not exported under ${conditions} from package ${request.descriptionFileRoot} (see exports field in ${request.descriptionFilePath})`,
+							`"${remainingRequest}" is not exported under ${conditionsStr} from package ${request.descriptionFileRoot} (see exports field in ${request.descriptionFilePath})`,
 						),
 					);
 				}