fix code action crash when diagnostic message is MarkupContent

Author: lukaszsamson

apps/language_server/lib/language_server/providers/code_action/helpers.ex

@@ -50,4 +50,14 @@ defmodule ElixirLS.LanguageServer.Providers.CodeAction.Helpers do
   defp maybe_recover_one_line_do(updated_text, _updated_ast) do
     updated_text
   end
+
+  # https://microsoft.github.io/language-server-protocol/specifications/lsp/3.18/specification/#diagnostic
+  # message can be string or MarkupContent
+  # string
+  def diagnostic_to_message(diagnostic) when is_binary(diagnostic), do: diagnostic
+
+  # MarkupContent
+  def diagnostic_to_message(%{"kind" => kind, "value" => value})
+      when kind in ["plaintext", "markdown"],
+      do: value
 end

apps/language_server/lib/language_server/providers/code_action/replace_remote_function.ex

@@ -30,7 +30,9 @@ defmodule ElixirLS.LanguageServer.Providers.CodeAction.ReplaceRemoteFunction do
   end
 
   defp extract_function_and_line(diagnostic) do
-    with {:ok, module, function, arity} <- extract_function(diagnostic["message"]) do
+    message = diagnostic_to_message(diagnostic)
+
+    with {:ok, module, function, arity} <- extract_function(message) do
       {:ok, module, function, arity, diagnostic["range"]["start"]["line"]}
     end
   end

apps/language_server/lib/language_server/providers/code_action/replace_with_underscore.ex

@@ -28,7 +28,9 @@ defmodule ElixirLS.LanguageServer.Providers.CodeAction.ReplaceWithUnderscore do
   end
 
   defp extract_variable_and_line(diagnostic) do
-    with {:ok, variable_name} <- extract_variable_name(diagnostic["message"]) do
+    message = diagnostic_to_message(diagnostic)
+
+    with {:ok, variable_name} <- extract_variable_name(message) do
       {:ok, variable_name, diagnostic["range"]["start"]["line"]}
     end
   end