Refactor: Removed generic errors

The fetch lib already contains them all

europeana.js

@@ -24,14 +24,6 @@ module.exports = class Europeana {
       wskey,
       timeout,
     };
-
-    this._errors = {
-      400: 'The request sent by the client was syntactically incorrect',
-      401: 'Authentication credentials were missing or authentication failed.',
-      404: 'The requested record was not found.',
-      429: 'The request could be served because the application has reached its usage limit.',
-      500: 'Internal Server Error. Something has gone wrong, please report to us.',
-    };
   }
 
 
@@ -116,8 +108,7 @@ module.exports = class Europeana {
 
     // HTML error
     if (body.match (/^</)) {
-      const msg = this._errors[res.status] || res.statusText;
-      const error = new Error (`API error: ${msg}`);
+      const error = new Error (`API error: ${res.statusText}`);
 
       error.code = res.status;
       throw error;