Fix tab-completion crash.

Author: kpeeters

client_server/ComputeThread.cc

@@ -283,22 +283,30 @@ void ComputeThread::on_message(websocketpp::connection_hdl hdl, message_ptr msg)
 		root=nlohmann::json::parse(msg->get_payload());
 		}
 	catch(nlohmann::json::exception& e) {
-		std::cerr << "cadabra-client: cannot parse message" << std::endl;
+		std::cerr << "cadabra-client: cannot parse message." << std::endl;
+		return;
+		}
+	if(root.count("header")==0) {
+		std::cerr << "cadabra-client: received message without 'header'." << std::endl;
+		return;
+		}
+	if(root.count("content")==0) {
+		std::cerr << "cadabra-client: received message without 'content'." << std::endl;
 		return;
 		}
 	const nlohmann::json& header  = root["header"];
 	const nlohmann::json& content = root["content"];
 	const std::string msg_type    = root.value("msg_type", "");
 
 	DataCell::id_t parent_id;
-	parent_id.id = header["parent_id"].get<uint64_t>();
+	parent_id.id = header.value("parent_id", uint64_t(0));
 	if(header.value("parent_origin", "")=="client")
 		parent_id.created_by_client=true;
 	else
 		parent_id.created_by_client=false;
 	DataCell::id_t cell_id;
 	cell_id.id = header["cell_id"].get<uint64_t>();
-	if(header["cell_origin"].get<std::string>()=="client")
+	if(header.value("cell_origin", "")=="client")
 		cell_id.created_by_client=true;
 	else
 		cell_id.created_by_client=false;

web2/cadabra2/source/download.html

@@ -48,6 +48,7 @@ <h2>Binary packages</h2>
 	 <div class="distronum"><a href="https://cadabra.science/packages/fedora28/">Fedora 28</a></div>
 	 <div class="distronum"><a href="https://cadabra.science/packages/fedora29/">Fedora 29</a></div>	 	 
 	 <div class="distronum"><a href="https://cadabra.science/packages/fedora32/">Fedora 32</a></div>	 	 
+	 <div class="distronum"><a href="https://cadabra.science/packages/fedora33/">Fedora 33</a></div>	 	 
 	 <div class="distrotxt">
 	 </div>
   </div>
@@ -58,7 +59,7 @@ <h2>Binary packages</h2>
 	 <div class="distronum"><a href="https://cadabra.science/packages/mint20/">Mint Ulyana 20</a></div>
   </div>
 
-  <div class="distrotype">
+<!--  <div class="distrotype">
 	 <img src="static/images/centoslogo.png"/>
 	 <div class="distronum"><a href="https://cadabra.science/packages/centos7/">CentOS 7</a></div>
 	 <div class="distrotxt">
@@ -78,7 +79,7 @@ <h2>Binary packages</h2>
 		  install python-pip; sudo pip install sympy</code>
 		in order to enable component computations.
 	 </div>
-  </div>
+  </div> -->
 
   <div class="distrotype">
 	 <img src="static/images/opensuse_logo.png"/>