Remove checks against very old config options and related cleanup

lib/cli.js

@@ -317,33 +317,17 @@ export default async function loadCli() { // eslint-disable-line complexity
 	}
 
 	if (Object.hasOwn(combined, 'concurrency') && (!Number.isInteger(combined.concurrency) || combined.concurrency < 0)) {
-		exit('The --concurrency or -c flag must be provided with a nonnegative integer.');
-	}
-
-	if (!combined.tap && Object.keys(experiments).length > 0) {
-		console.log(chalk.magenta(`  ${figures.warning} Experiments are enabled. These are unsupported and may change or be removed at any time.`));
-	}
-
-	if (Object.hasOwn(conf, 'babel')) {
-		exit('Built-in Babel support has been removed.');
-	}
-
-	if (Object.hasOwn(conf, 'compileEnhancements')) {
-		exit('Enhancement compilation must be configured in AVA’s Babel options.');
-	}
-
-	if (Object.hasOwn(conf, 'helpers')) {
-		exit('AVA no longer compiles helpers. Add exclusion patterns to the ’files’ configuration and specify ’compileAsTests’ in the Babel options instead.');
-	}
-
-	if (Object.hasOwn(conf, 'sources')) {
-		exit('’sources’ has been removed. Use ’ignoredByWatcher’ to provide glob patterns of files that the watcher should ignore.');
+		exit('The --concurrency or -c flag must be provided with a non-negative integer.');
 	}
 
 	if (Object.hasOwn(conf, 'sortTestFiles') && typeof conf.sortTestFiles !== 'function') {
 		exit('’sortTestFiles’ must be a comparator function.');
 	}
 
+	if (!combined.tap && Object.keys(experiments).length > 0) {
+		console.log(chalk.magenta(`  ${figures.warning} Experiments are enabled. These are unsupported and may change or be removed at any time.`));
+	}
+
 	let projectPackageObject;
 	try {
 		projectPackageObject = JSON.parse(fs.readFileSync(path.resolve(projectDir, 'package.json')));

test/concurrency/snapshots/test.js.md

@@ -8,22 +8,22 @@ Generated by [AVA](https://avajs.dev).
 
 > fails with message
 
-    'The --concurrency or -c flag must be provided with a nonnegative integer.'
+    'The --concurrency or -c flag must be provided with a non-negative integer.'
 
 ## bails when --concurrency is provided with an input that is a string
 
 > fails with message
 
-    'The --concurrency or -c flag must be provided with a nonnegative integer.'
+    'The --concurrency or -c flag must be provided with a non-negative integer.'
 
 ## bails when --concurrency is provided with an input that is a float
 
 > fails with message
 
-    'The --concurrency or -c flag must be provided with a nonnegative integer.'
+    'The --concurrency or -c flag must be provided with a non-negative integer.'
 
 ## bails when --concurrency is provided with an input that is negative
 
 > fails with message
 
-    'The --concurrency or -c flag must be provided with a nonnegative integer.'
+    'The --concurrency or -c flag must be provided with a non-negative integer.'