improve "Browser client is out of date" error message

Author: sorenlouv

src/legacy/server/http/version_check.js

@@ -27,10 +27,13 @@ export function setupVersionCheck(server, config) {
     const versionRequested = req.headers[versionHeader];
 
     if (versionRequested && versionRequested !== actualVersion) {
-      throw badRequest('Browser client is out of date, please refresh the page', {
-        expected: actualVersion,
-        got: versionRequested
-      });
+      throw badRequest(
+        `Browser client is out of date, please refresh the page (Header "${versionHeader}" was ${versionRequested} but should be ${actualVersion})`,
+        {
+          expected: actualVersion,
+          got: versionRequested,
+        }
+      );
     }
 
     return h.continue;