Build: align eslint config with 3.x branch as much as possible

Close gh-5524

build/release/dist.js

@@ -24,6 +24,7 @@ const distRepoFolder = "tmp/release/dist";
 
 // Files to be included in the dist repo.
 // README.md and bower.json are generated.
+// package.json is a simplified version of the original.
 const files = [
 	"dist",
 	"dist-module",

eslint.config.js

@@ -10,7 +10,7 @@ export default [
 		// See https://github.com/eslint/eslint/discussions/17412
 		ignores: [
 			"external",
-			"**/tmp",
+			"tmp",
 			"test/data/json_obj.js",
 			"test/data/jquery-*.js"
 		]
@@ -67,6 +67,10 @@ export default [
 				}
 			],
 			"no-implicit-globals": "error",
+			"no-unused-vars": [
+				"error",
+				{ caughtErrorsIgnorePattern: "^_" }
+			],
 			"one-var": [ "error", { var: "always" } ],
 			strict: [ "error", "function" ]
 		}
@@ -298,6 +302,10 @@ export default [
 		rules: {
 			...jqueryConfig.rules,
 			"no-implicit-globals": "error",
+			"no-unused-vars": [
+				"error",
+				{ caughtErrorsIgnorePattern: "^_" }
+			],
 			strict: [ "error", "global" ]
 		}
 	},
@@ -332,6 +340,11 @@ export default [
 			// That is okay for the built version
 			"no-multiple-empty-lines": "off",
 
+			"no-unused-vars": [
+				"error",
+				{ caughtErrorsIgnorePattern: "^_" }
+			],
+
 			// When custom compilation is used, the version string
 			// can get large. Accept that in the built version.
 			"max-len": "off",