Enhance error handling in OxiAPI and Node classes

- Updated the `reload` method in the `OxiAPI` class to catch `HTTPError` exceptions and raise a custom `OxiAPIError` with context.
- Improved the `__call__` method in the `Node` class to handle `HTTPError` exceptions similarly, providing context-specific error messages.
- Introduced a new class method `from_http_error` in `OxiAPIError` for standardized error message generation based on HTTP status codes.

oxi/exception.py

@@ -1,4 +1,16 @@
-from typing import Optional
+from typing import TYPE_CHECKING, Optional
+
+if TYPE_CHECKING:
+    from requests import HTTPError
+
+_STATUS_MESSAGES: dict[int, str] = {
+    401: "Unauthorized",
+    403: "Forbidden",
+    500: "Internal Server Error",
+    502: "Bad Gateway",
+    503: "Service Unavailable",
+    504: "Gateway Timeout",
+}
 
 
 class OxiAPIError(Exception):
@@ -10,3 +22,13 @@ class OxiAPIError(Exception):
         if self.status_code is not None:
             return f"OxiAPIError: {self.args[0]} (HTTP {self.status_code})"
         return f"OxiAPIError: {self.args[0]}"
+
+    @classmethod
+    def from_http_error(cls, e: "HTTPError", context: str = "") -> "OxiAPIError":
+        status = e.response.status_code
+        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}"
+            message = f"{context}: {base}" if context else base
+        return cls(message, status)