add: no assistant bug docs

docs/docs/guides/error-codes/no-assistant-available.mdx

@@ -0,0 +1,31 @@
+---
+title: No assistant available
+slug: /troubleshooting/no-assistant-available
+description: Troubleshooting steps to resolve issues related to loading model.
+keywords:
+  [
+    Jan AI,
+    Jan,
+    ChatGPT alternative,
+    local AI,
+    private AI,
+    conversational AI,
+    no-subscription fee,
+    large language model,
+    troubleshooting,
+  ]
+---
+
+
+When you encounter the following error message:
+```
+No assistant available.
+```
+
+This issue arises when a new, unintentional file appears in `/jan/assistants`.
+
+It can be resolved through the following steps:
+
+1. Access the `/jan/assistants` directory using a file manager or terminal.
+
+2. Within `/jan/assistants`, this directory should only contain a folder named `jan`. Identify any file outside of this folder and remove it.