Use safeTraverse where appropriate

lib/transformations/removeDeprecatedPlugins/__snapshots__/removeDeprecatedPlugins.test.js.snap

@@ -30,3 +30,15 @@ export default (config) => {
 }
 "
 `;
+
+exports[`removeDeprecatedPlugins transforms correctly using "removeDeprecatedPlugins-4" data 1`] = `
+"// This should throw
+const inst = new webpack.optimize.OccurrenceOrderPlugin()
+export default (config) => {
+    config.plugins = [
+        inst
+    ]
+    return config
+}
+"
+`;

lib/transformations/removeDeprecatedPlugins/__testfixtures__/removeDeprecatedPlugins-4.input.js

@@ -0,0 +1,8 @@
+// This should throw
+const inst = new webpack.optimize.OccurrenceOrderPlugin()
+export default (config) => {
+    config.plugins = [
+        inst
+    ]
+    return config
+}

lib/transformations/removeDeprecatedPlugins/removeDeprecatedPlugins.js

@@ -19,13 +19,12 @@ module.exports = function(j, ast, source) {
 	return utils.findPluginsByName(j, ast, deprecatedPlugingsList)
 		.forEach(path => {
 			// For now we only support the case there plugins are defined in an Array
-			if (path.parent &&
-				path.parent.value &&
-				utils.isType(path.parent.value, 'ArrayExpression')
-			) {
+			const arrayPath = utils.safeTraverse(path, ['parent','value']);
+			if (arrayPath && utils.isType(arrayPath, 'ArrayExpression')) {
 				// Check how many plugins are defined and
 				// if there is only last plugin left remove `plugins: []` node
-				if (path.parent.value.elements.length === 1) {
+				const arrayElementsPath = utils.safeTraverse(arrayPath, ['elements']);
+				if (arrayElementsPath && arrayElementsPath.length === 1) {
 					j(path.parent.parent).remove();
 				} else {
 					j(path).remove();

lib/transformations/removeDeprecatedPlugins/removeDeprecatedPlugins.test.js

@@ -4,3 +4,4 @@ defineTest(__dirname, 'removeDeprecatedPlugins', 'removeDeprecatedPlugins-0');
 defineTest(__dirname, 'removeDeprecatedPlugins', 'removeDeprecatedPlugins-1');
 defineTest(__dirname, 'removeDeprecatedPlugins', 'removeDeprecatedPlugins-2');
 defineTest(__dirname, 'removeDeprecatedPlugins', 'removeDeprecatedPlugins-3');
+defineTest(__dirname, 'removeDeprecatedPlugins', 'removeDeprecatedPlugins-4');