Log OAuth token errors

app/src/main/java/eu/faircode/email/GmailState.java

@@ -122,7 +122,8 @@ public class GmailState {
         if (newToken != null && !newToken.equals(token)) {
             token = newToken;
             acquired = new Date().getTime();
-        }
+        } else
+            Log.e("Token refresh failed id=" + id + " token=" + (token != null));
 
         if (token == null)
             throw new AuthenticatorException("No token for " + id + ":" + user);

app/src/main/java/eu/faircode/email/ServiceAuthenticator.java

@@ -219,8 +219,10 @@ public class ServiceAuthenticator extends Authenticator {
             semaphore.acquire();
             Log.i("OAuth refreshed user=" + id + ":" + user);
 
-            if (holder.error != null)
+            if (holder.error != null) {
+                Log.e(new Throwable("Token refresh failed id=" + id, holder.error));
                 throw holder.error;
+            }
         } catch (Exception ex) {
             throw new MessagingException("OAuth refresh id=" + id, ex);
         }