feat: add custom UnknownEditFormat exception with documentation link

aider/coders/base_coder.py

@@ -22,7 +22,7 @@ from typing import List
 from aider import __version__, models, prompts, urls, utils
 from aider.analytics import Analytics
 from aider.commands import Commands
-from aider.exceptions import LiteLLMExceptions
+from aider.exceptions import LiteLLMExceptions, UnknownEditFormat
 from aider.history import ChatSummary
 from aider.io import ConfirmGroup, InputOutput
 from aider.linter import Linter
@@ -157,7 +157,8 @@ class Coder:
                 res.original_kwargs = dict(kwargs)
                 return res
 
-        raise ValueError(f"Unknown edit format {edit_format}")
+        valid_formats = [c.edit_format for c in coders.__all__ if hasattr(c, "edit_format")]
+        raise UnknownEditFormat(edit_format, valid_formats)
 
     def clone(self, **kwargs):
         new_coder = Coder.create(from_coder=self, **kwargs)

aider/main.py

@@ -765,6 +765,10 @@ def main(argv=None, input=None, output=None, force_git_root=None, return_coder=F
             chat_language=args.chat_language,
             detect_urls=args.detect_urls,
         )
+    except UnknownEditFormat as err:
+        io.tool_error(str(err))
+        io.offer_url(urls.edit_formats, "Open documentation about edit formats?")
+        return 1
     except ValueError as err:
         io.tool_error(str(err))
         return 1

aider/urls.py

@@ -13,3 +13,4 @@ git_index_version = "https://github.com/Aider-AI/aider/issues/211"
 install_properly = "https://aider.chat/docs/troubleshooting/imports.html"
 analytics = "https://aider.chat/docs/more/analytics.html"
 release_notes = "https://aider.chat/HISTORY.html#release-notes"
+edit_formats = "https://aider.chat/docs/more/edit-formats.html"