improve TypeError message

by using `inspect-with-kind`

https://github.com/shinnn/inspect-with-kind

index.js

@@ -1,18 +1,21 @@
 'use strict';
 
 const frontMatter = require('front-matter');
+const inspectWithKind = require('inspect-with-kind');
 const objectPath = require('object-path');
 const PluginError = require('plugin-error');
 const Transform = require('stream').Transform;
 const VinylBufferStream = require('vinyl-bufferstream');
 
+const PROPERTY_ERROR = 'Expected `property` option to be a string';
+
 module.exports = function gulpFrontMatter(options) {
 	options = Object.assign({property: 'frontMatter'}, options);
 
 	if (typeof options.property !== 'string') {
-		throw new PluginError('gulp-front-matter', new TypeError(`${
-			options.property
-		} is not a string. "property" option must be a string.`));
+		throw new PluginError('gulp-front-matter', new TypeError(`${PROPERTY_ERROR}, but a non-string value ${
+			inspectWithKind(options.property)
+		} was provided.`));
 	}
 
 	return new Transform({

package.json

@@ -33,6 +33,7 @@
 	"license": "BSD-2-Clause",
 	"dependencies": {
 		"front-matter": "^2.3.0",
+		"inspect-with-kind": "^1.0.4",
 		"object-path": "^0.11.4",
 		"plugin-error": "^0.1.2",
 		"vinyl-bufferstream": "^1.0.1"

test.js

@@ -136,7 +136,7 @@ test('gulp-front-matter', t => {
 
 	t.throws(
 		() => gulpFrontMatter({property: 1}),
-		/.*is not a string.*must be a string/,
+		/Expected `property` option to be a string, but a non-string value 1 \(number\) was provided\./,
 		'should throw a plugin error when `property` option is not a string.'
 	);
 });