Implement enhanced error detection for NodeNotFound in OxiAPIError

- Added a new helper function `_looks_like_node_not_found_html` to identify NodeNotFound errors based on HTTP response content.
- Updated the `from_http_error` method in the `OxiAPIError` class to convert 500 status codes to 404 when a NodeNotFound error is detected, improving error handling and user feedback.

oxi/exception.py

@@ -13,10 +13,32 @@ _STATUS_MESSAGES: dict[int, str] = {
 }
 
 
+def _looks_like_node_not_found_html(e: "HTTPError") -> bool:
+    resp = getattr(e, "response", None)
+    if resp is None:
+        return False
+    try:
+        content_type = (resp.headers or {}).get("Content-Type", "")
+    except Exception:
+        content_type = ""
+    if "text/html" not in (content_type or "").lower():
+        return False
+    try:
+        body = (resp.text or "")[:20_000]
+    except Exception:
+        return False
+    return (
+        "Oxidized::NodeNotFound" in body
+        or "NodeNotFound" in body
+        or "<title>Oxidized::NodeNotFound" in body
+    )
+
+
 class OxiAPIError(Exception):
     def __init__(self, message: str, status_code: Optional[int] = None):
         super().__init__(message)
         self.status_code = status_code
+        self.message = message
 
     def __str__(self):
         if self.status_code is not None:
@@ -25,10 +47,19 @@ class OxiAPIError(Exception):
 
     @classmethod
     def from_http_error(cls, e: "HTTPError", context: str = "") -> "OxiAPIError":
-        status = e.response.status_code
+        resp = getattr(e, "response", None)
+        status = resp.status_code if resp is not None else None
+
+        if status == 500 and _looks_like_node_not_found_html(e):
+            status = 404
+
         if status == 404:
             message = f"{context} not found" if context else "Not found"
         else:
-            base = _STATUS_MESSAGES.get(status) or e.response.reason or f"HTTP {status}"
+            base = (
+                (_STATUS_MESSAGES.get(status) if status is not None else None)
+                or (resp.reason if resp is not None else None)
+                or (f"HTTP {status}" if status is not None else "Request failed")
+            )
             message = f"{context}: {base}" if context else base
         return cls(message, status)