feat: add ESlint rule no-sparse-arrays for config check

Author: KristjanESPERANTO

CHANGELOG.md

@@ -19,6 +19,8 @@ planned for 2026-01-01
 
 ### Fixed
 
+- feat: add ESlint rule `no-sparse-arrays` for config check to fix #3910 (#3911)
+
 ### Updated
 
 - [core] Update dependencies (#3909)

js/check_config.js

@@ -58,7 +58,10 @@ function checkConfigFile () {
 					...globals.node
 				}
 			},
-			rules: { "no-undef": "error" }
+			rules: {
+				"no-sparse-arrays": "error",
+				"no-undef": "error"
+			}
 		},
 		configFileName
 	);