ConnectionManager: fail if max channel count is reached

Change-Id: I71d88e0efbf78009ba003b03d107c0f897dbc485
diff --git a/src/connectionmanager.cpp b/src/connectionmanager.cpp
index 2eb0a1c..f49834e 100644
--- a/src/connectionmanager.cpp
+++ b/src/connectionmanager.cpp
@@ -1041,6 +1041,13 @@
                                             const dht::Value::Id& vid)
 {
     auto channelSock = sock->addChannel(name);
+    if (!channelSock) {
+        if (config_->logger)
+            config_->logger->error("sendChannelRequest failed - cannot create channel");
+        if (auto info = dinfo.lock())
+            info->executePendingOperations(vid, nullptr);
+        return;
+    }
     channelSock->onShutdown([dinfo, name, vid] {
         if (auto info = dinfo.lock())
             info->executePendingOperations(vid, nullptr);