extend error except, add saving to a file of processed pairlist + docs

docs/includes/pairlists.md

@@ -192,7 +192,8 @@ The RemotePairList is defined in the pairlists section of the configuration sett
         "refresh_period": 1800,
         "keep_pairlist_on_failure": true,
         "read_timeout": 60,
-        "bearer_token": "my-bearer-token"
+        "bearer_token": "my-bearer-token",
+        "save_to_file": "user_data/filename.json" 
     }
 ]
 ```
@@ -207,6 +208,8 @@ In "append" mode, the retrieved pairlist is added to the original pairlist. All
 
 The `pairlist_url` option specifies the URL of the remote server where the pairlist is located, or the path to a local file (if file:/// is prepended). This allows the user to use either a remote server or a local file as the source for the pairlist.
 
+The `save_to_file` option, when provided with a valid filename, saves the processed pairlist to that file in JSON format. This option is optional, and by default, the pairlist is not saved.
+
 The user is responsible for providing a server or local file that returns a JSON object with the following structure:
 
 ```json

freqtrade/plugins/pairlist/RemotePairList.py

@@ -52,6 +52,7 @@ class RemotePairList(IPairList):
         self._read_timeout = self._pairlistconfig.get('read_timeout', 60)
         self._bearer_token = self._pairlistconfig.get('bearer_token', '')
         self._init_done = False
+        self._save_to_file = self._pairlistconfig.get('save_to_file', None)
         self._last_pairlist: List[Any] = list()
 
         if self._mode not in ['whitelist', 'blacklist']:
@@ -236,15 +237,15 @@ class RemotePairList(IPairList):
 
                 if file_path.exists():
                     with file_path.open() as json_file:
-                        # Load the JSON data into a dictionary
-                        jsonparse = rapidjson.load(json_file, parse_mode=CONFIG_PARSE_MODE)
-
                         try:
+                            # Load the JSON data into a dictionary
+                            jsonparse = rapidjson.load(json_file, parse_mode=CONFIG_PARSE_MODE)
                             pairlist = self.process_json(jsonparse)
                         except Exception as e:
                             if self._init_done:
                                 pairlist = self.return_last_pairlist()
                                 logger.warning(f'Error while processing JSON data: {type(e)}')
+                                logger.debug(f'Error while processing JSON data: {e}')
                             else:
                                 raise OperationalException('Error while processing'
                                                            f'JSON data: {type(e)}')
@@ -273,8 +274,24 @@ class RemotePairList(IPairList):
 
         self._last_pairlist = list(pairlist)
 
+        if self._save_to_file:
+            self.save_pairlist(pairlist, self._save_to_file)
+
         return pairlist
 
+    def save_pairlist(self, pairlist: List[str], filename: str) -> None:
+        pairlist_data = {
+            "pairs": pairlist,
+            "refresh_period": self._refresh_period
+        }
+        try:
+            file_path = Path(filename)
+            with file_path.open('w') as json_file:
+                rapidjson.dump(pairlist_data, json_file)
+                logger.info(f"Processed pairlist saved to {filename}")
+        except Exception as e:
+            logger.error(f"Error saving processed pairlist to {filename}: {e}")
+
     def filter_pairlist(self, pairlist: List[str], tickers: Dict) -> List[str]:
         """
         Filters and sorts pairlist and returns the whitelist again.