add 'output.errorfile' config option

docs/configuration.rst

@@ -4408,6 +4408,21 @@ Description
     The default format string here is ``"{message}"``.
 
 
+output.errorfile
+----------------
+Type
+    |Path|_
+Description
+    File to write input URLs which returned an error to.
+
+    When combined with
+    ``-I``/``--input-file-comment`` or
+    ``-x``/``--input-file-delete``,
+    this option will cause all input URLs from these files
+    to be commented/deleted after processing them
+    and not just successful ones.
+
+
 output.num-to-str
 -----------------
 Type

gallery_dl/__init__.py

@@ -249,8 +249,10 @@ def main():
                         input_log.error(exc)
                         return getattr(exc, "code", 128)
 
-            if args.error_file:
+            error_file = (args.error_file or
-                input_manager.error_file(args.error_file)
+                          config.get(("output",), "errorfile"))
+            if error_file:
+                input_manager.error_file(error_file)
 
             pformat = config.get(("output",), "progress", True)
             if pformat and len(input_manager.urls) > 1 and \