Require Node.js 6

.gitattributes

@@ -1,2 +1 @@
-* text=auto
-*.js text eol=lf
+* text=auto eol=lf

.travis.yml

@@ -1,5 +1,5 @@
 language: node_js
 node_js:
+  - '10'
   - '8'
   - '6'
-  - '4'

index.js

@@ -13,7 +13,7 @@ function relPath(base, filePath) {
 	filePath = filePath.replace(/\\/g, '/');
 	base = base.replace(/\\/g, '/');
 
-	if (filePath.indexOf(base) !== 0) {
+	if (!filePath.startsWith(base)) {
 		return filePath;
 	}
 
@@ -85,7 +85,7 @@ const plugin = () => {
 			// Attempt to parse the sourcemap's JSON to get the reverse filename
 			try {
 				reverseFilename = JSON.parse(file.contents.toString()).file;
-			} catch (err) {}
+			} catch (_) {}
 
 			if (!reverseFilename) {
 				reverseFilename = path.relative(path.dirname(file.path), path.basename(file.path, '.map'));
@@ -148,7 +148,7 @@ plugin.manifest = (pth, opts) => {
 
 				try {
 					oldManifest = opts.transformer.parse(manifestFile.contents.toString());
-				} catch (err) {}
+				} catch (_) {}
 
 				manifest = Object.assign(oldManifest, manifest);
 			}

package.json

@@ -10,7 +10,7 @@
     "url": "sindresorhus.com"
   },
   "engines": {
-    "node": ">=4"
+    "node": ">=6"
   },
   "scripts": {
     "test": "xo && ava"
@@ -35,7 +35,7 @@
   ],
   "dependencies": {
     "modify-filename": "^1.1.0",
-    "plugin-error": "^0.1.2",
+    "plugin-error": "^1.0.1",
     "rev-hash": "^2.0.0",
     "rev-path": "^2.0.0",
     "sort-keys": "^2.0.0",