fix crash on malformed json (again)

docs/changelog.txt

@@ -44,6 +44,7 @@ changelog.txt uses a syntax similar to RST, with a few special sequences:
 - `work-now`: reinstated, renamed from ``workNow``: reduce the time that dwarves are left without a task after completing a job
 
 ## Fixes
+- RemoteServer: fix crash on malformed json in ``dfhack-config/remote-server.json``
 
 ## Misc Improvements
 - Terminal console no longer appears in front of the game window on startup

library/RemoteClient.cpp

@@ -150,7 +150,11 @@ int RemoteClient::GetDefaultPort()
             if (in_file)
             {
                 Json::Value config;
+                try {
                     in_file >> config;
+                } catch (const std::exception & e) {
+                    std::cerr << "Error reading remote server config file: " << filename << ": " << e.what() << std::endl;
+                }
                 in_file.close();
                 if (config.isMember("port")) {
                     port = config["port"].asInt();

library/RemoteServer.cpp

@@ -420,17 +420,20 @@ ServerMainImpl::ServerMainImpl(std::promise<bool> promise, int port) :
 
     Json::Value configJson;
 
-    std::ifstream inFile(filename, std::ios_base::in);
-
     bool allow_remote = false;
 
+    std::ifstream inFile(filename, std::ios_base::in);
+    try {
         if (inFile.is_open())
         {
             inFile >> configJson;
-        inFile.close();
-
             allow_remote = configJson.get("allow_remote", "false").asBool();
         }
+    } catch (const std::exception & e) {
+        std::cerr << "Error reading remote server config file: " << filename << ": " << e.what() << std::endl;
+        std::cerr << "Reverting to remote server config to defaults" << std::endl;
+    }
+    inFile.close();
 
     // rewrite/normalize config file
     configJson["allow_remote"] = allow_remote;