Added early exit for unreachable Ollama

Core/src/main/java/me/neurodock/core/Core.java

@@ -401,6 +401,32 @@ public class Core {
         }));
     }
 
+    /**
+     * A check to exit early if Ollama isn't reachable.
+     */
+    private void confirmOllama()
+    {
+        try {
+            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
+            connection.setRequestMethod("GET");
+            connection.setRequestProperty("Content-Type", "application/json");
+            connection.setDoOutput(true);
+            connection.setConnectTimeout(3 * 1000);
+
+            int responseCode = connection.getResponseCode();
+
+            if (responseCode != HttpURLConnection.HTTP_OK) {
+                new RuntimeException("Ollama is un-responsive on url: " + url.toString()).printStackTrace();
+                System.exit(1);
+            }
+        }catch (IOException ex)
+        {
+            ex.printStackTrace();
+            System.out.println("Can not reach Ollama!");
+            System.exit(1);
+        }
+    }
+
     /**
      * Creates a new instance of Core with the provided PrintMessageHandler,
      * defaulting the Ollama backend to {@code localhost}.
@@ -425,6 +451,7 @@ public class Core {
 
         initDirectories();
         initOllamaUrl();
+        confirmOllama();
         initLogWriter();
         initScheduler();
         initShutdownHook();