Remove underline from Babel configuration validation errors

This prevents us from processing the configuration in the ESLint helper, since the helper does not configure Chalk.

lib/babel-pipeline.js

@@ -12,7 +12,6 @@ const pkgConf = require('pkg-conf');
 const stripBomBuf = require('strip-bom-buf');
 const writeFileAtomic = require('write-file-atomic');
 const pkg = require('../package.json');
-const chalk = require('./chalk').get();
 
 function getSourceMap(filePath, code) {
 	let sourceMap = convertSourceMap.fromSource(code);
@@ -50,7 +49,7 @@ function validate(conf) {
 		(conf.testOptions !== undefined && !isPlainObject(conf.testOptions)) ||
 		(conf.extensions !== undefined && !isValidExtensions(conf.extensions))
 	) {
-		throw new Error(`Unexpected Babel configuration for AVA. See ${chalk.underline(`https://github.com/avajs/ava/blob/v${pkg.version}/docs/recipes/babel.md`)} for allowed values.`);
+		throw new Error(`Unexpected Babel configuration for AVA. See https://github.com/avajs/ava/blob/v${pkg.version}/docs/recipes/babel.md for allowed values.`);
 	}
 
 	return {