Name the unexpected keyword argument in the bind-failure TypeError - #144

What does this implement/fix? Explain your changes.

When a call fails to bind because of a misspelled keyword argument, the error did not mention the kwarg at all — only positional argument types are echoed — so the actual mistake was invisible:

market_order(symbol, -10, as_tag="EmergencyFlatten")
TypeError: No method matches given arguments for market_order: (<class 'QuantConnect.Symbol'>, <class 'int'>). The following overloads are available: ...

Cause: MethodBinder.Invoke's bind-failure path builds its message from the positional args tuple only and has no unexpected-keyword-argument path.

The fix:

• MethodBinder.AppendUnexpectedKeywordArgument runs while the bind-failure message is built: when a supplied kwarg name is accepted by no candidate overload (same candidate set Bind used, so snake_case and original parameter names are matched exactly like binding does), it extends the existing message — right after the positional argument types, before the overload list — naming the first unknown kwarg in call order like CPython:

  TypeError: No method matches given arguments for market_order: (<class 'QuantConnect.Symbol'>, <class 'int'>). Got an unexpected keyword argument 'as_tag'. Did you mean 'tag'? The following overloads are available: ...
  

• The Did you mean hint suggests the closest parameter name across all overloads (small local Levenshtein plus containment for 3+ character names); it is omitted when nothing is similar.

• When every kwarg name is valid for some overload but binding still fails (e.g. a type mismatch, or an argument supplied both positionally and by name), the message is unchanged.

• The whole message-construction block (including the pre-existing name/argument-types/overloads parts) is now wrapped in a try/catch: it runs over arbitrary caller input inside the tp_call slot, where an escaping exception would propagate into CPython and mask the bind failure; on error the TypeError is raised with whatever was appended so far.

A complete message as produced against the new test fixture:

TypeError: No method matches given arguments for order_like_method: (<class 'str'>, <class 'int'>). Got an unexpected keyword argument 'as_tag'. Did you mean 'tag'? The expected signature is:
  order_like_method(symbol: str, quantity: float, asynchronous: bool = False, tag: str = "", order_properties: Any = None)

Note: the message keeps the No method matches given arguments for {name}: prefix, so Lean's NoMethodMatchPythonExceptionInterpreter keeps matching and rewriting it exactly as before; the kwarg detail rides along inside it.

Note on #147: ClassBase's private LevenshteinDistance moved verbatim to Util.LevenshteinDistance, used by both ClassBase and MethodBinder. #147 deletes the ClassBase call site in favor of Jaro-Winkler; the shared helper remains for MethodBinder, so the merge interplay is a trivial deletion on their side.

Does this close any currently open issues?

No. Part of the error-surface improvements from QuantConnect/Agents#305 (improvement 1: fleet evidence A-70ad2e3b).

Any other comments?

Tests:

• test_unexpected_keyword_argument_with_suggestion: unknown kwarg via both the snake_case and original PascalCase method names; asserts the no-match prefix is kept, the kwarg is named, and Did you mean 'tag'? is suggested.
• test_unexpected_keyword_argument_without_suggestion: unrelated kwarg name; asserts no Did you mean hint.
• test_unexpected_keyword_argument_reports_first_in_call_order: two unknown kwargs; asserts the first is reported.
• test_valid_keyword_arguments_still_bind: valid kwargs on the new fixture method bind and execute.
• test_valid_keyword_argument_names_keep_no_match_message: valid kwarg names with an unbindable call keep the classic no-method-matches message with no kwarg detail appended.
• Full python suite (py -3.11 -m pytest --runtime netcore tests): 461 passed, 23 skipped, 1 failed — the failure (test_explicit_assembly_load) is environmental and fails identically on unmodified master.
• Full embed suite (dotnet test src/embed_tests -c Release): 971 passed, 0 failed, 8 skipped.

Checklist

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