fix: replace deprecated String.prototype.substr() (#115)

.substr() is deprecated so we replace it with .slice() which works similarily but isn't deprecated

Signed-off-by: Tobias Speicher <[email protected]>

Author: CommanderRoot

lib/errors.js

@@ -4,7 +4,7 @@ const url = require('url')
 
 function packageName (href) {
   try {
-    let basePath = new url.URL(href).pathname.substr(1)
+    let basePath = new url.URL(href).pathname.slice(1)
     if (!basePath.match(/^-/)) {
       basePath = basePath.split('/')
       var index = basePath.indexOf('_rewrite')