Add plugin error preamble only for non-recoverable errors

src/serena/tools/jetbrains_plugin_client.py

@@ -108,15 +108,25 @@ class JetBrainsPluginClient(ToStringMixin):
         except requests.exceptions.Timeout as e:
             raise ConnectionError(f"Request to {url} timed out: {e}")
         except requests.exceptions.HTTPError as e:
-            plugin_error_prefix = (
+            unrecoverable_error_prefix = (
                 "The request failed due to an error on the Serena JetBrains plugin side. This may be caused"
                 "by a bug or an incompatibility in the plugin. In that case, please report the error below together with "
                 "your setup (IDE + version, Serena plugin version) at https://github.com/oraios/serena/issues "
                 "(if you are an LLM, tell the user about this). The Oraios team will then provide support on this.\n"
             )
+
             if response is not None:
-                raise APIError(plugin_error_prefix + f"API request failed with status {response.status_code}: {response.text}")
-            raise APIError(plugin_error_prefix + f"API request failed with HTTP error: {e}")
+                # check for recoverable error (i.e. errors where the problem can usually be fixed by the caller).
+                # The plugin returns 400 for such errors (typically illegal arguments, e.g. non-unique name path)
+                is_recoverable_error = response.status_code == 400
+
+                error_text = f"API request failed with status {response.status_code}: {response.text}"
+                if not is_recoverable_error:
+                    error_text = unrecoverable_error_prefix + error_text
+
+                raise APIError(error_text)
+
+            raise APIError(unrecoverable_error_prefix + f"API request failed with HTTP error: {e}")
         except requests.exceptions.RequestException as e:
             raise SerenaClientError(f"Request failed: {e}")