problem: clients locks forever if auth failed

solution: put auth errors to stderr and clear auth queue on errors (so it can reauth later)

Author: splix

emerald-api/src/main/java/io/emeraldpay/impl/AuthHolder.java

@@ -86,7 +86,12 @@ public void setAuth(MetadataHandler auth) {
             this.auth = auth;
             if (auth.isReady()) {
                 for (Consumer<MetadataHandler> listener : authQueue) {
-                    listener.accept(auth);
+                    try {
+                        listener.accept(auth);
+                    } catch (Exception e) {
+                        System.err.println("Error in auth listener: " + e.getMessage());
+                        // ignore any exceptions in the listener, it should not block the auth update
+                    }
                 }
                 authQueue.clear();
             }

emerald-api/src/main/java/io/emeraldpay/impl/TokenCredentials.java

@@ -137,10 +137,15 @@ public boolean isReady() {
     @Override
     public void request(AuthHolder caller) {
         executor.submit(() -> {
-            if (jwt == null) {
-                authSync();
-            } else {
-                refreshSync();
+            try {
+                if (jwt == null) {
+                    authSync();
+                } else {
+                    refreshSync();
+                }
+            } catch (Exception e) {
+                System.err.println("Error during the authentication: " + e.getMessage());
+                return;
             }
             caller.setAuth(this);
         });