Improve error tracking on private network.

CHANGELOG.md

@@ -15,6 +15,7 @@ This package follows standard semvar, `<major>.<minor>.<build>`. No breaking cha
 * Add missing link to Tag display page.
 * Replace `replaceState` with `pushState` so forwards and backwards navigation actually work.
 * Add id and name for autocomplete options.
+* Improve error on Access-Control-Allow-Private-Network.
 
 ## 2.1
 * Add `x-locale` vendor extension to specify the locale of the spec.

src/utils/spec-parser.js

@@ -23,7 +23,11 @@ export default async function ProcessSpec(specUrlOrObject, serverUrl = '') {
 
   if (!jsonParsedSpec) {
     if (errorToDisplay) {
-      throw Error(`Failed to resolve the spec: ${errorToDisplay}`);
+      if (inputSpecIsAUrl && specUrlOrObject.toString().match('localhost')) {
+        throw Error(`Cannot connect to your localhost running spec because your webserver is blocking requests. To the load the spec from ${specUrlOrObject.toString()}, return the following CORS header \`"Access-Control-Allow-Private-Network": "true"\`.`);
+      }
+      const message = `Failed to resolve the spec: ${errorToDisplay}`;
+      throw Error(message);
     }
     throw Error('SpecificationNotFound');
   }