feat(provider): initial error handling on claude (#221)

* fix: improve error handling for common issues

* fix: Providers.on_error for handling API errors

* Update lua/avante/providers/init.lua

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Co-authored-by: Aaron Pham <Aaronpham0103@gmail.com>

lua/avante/providers/init.lua

@@ -72,6 +72,7 @@ local Dressing = require("avante.ui.dressing")
 ---@field model? string
 ---@field parse_api_key fun(): string | nil
 ---@field parse_stream_data? AvanteStreamParser
+---@field on_error? fun(result: table): nil
 ---
 ---@class avante.Providers
 ---@field openai AvanteProviderFunctor