Fix crash in callback suggestions

Fix formatting of types matching locals without parens
Fixes #235

lib/elixir_sense/core/introspection.ex

@@ -813,15 +813,36 @@ defmodule ElixirSense.Core.Introspection do
   defp drop_macro_env(other), do: other
 
   defp get_typespec_signature({:when, _, [{:"::", _, [{name, meta, args}, _]}, _]}, arity) do
-    Macro.to_string({name, meta, strip_types(args, arity)})
+    to_string_with_parens({name, meta, strip_types(args, arity)})
   end
 
   defp get_typespec_signature({:"::", _, [{name, meta, args}, _]}, arity) do
-    Macro.to_string({name, meta, strip_types(args, arity)})
+    to_string_with_parens({name, meta, strip_types(args, arity)})
   end
 
   defp get_typespec_signature({name, meta, args}, arity) do
-    Macro.to_string({name, meta, strip_types(args, arity)})
+    to_string_with_parens({name, meta, strip_types(args, arity)})
+  end
+
+  def to_string_with_parens({name, meta, args}) when is_atom(name) do
+    if Code.Formatter.local_without_parens?(
+         name,
+         length(args),
+         Code.Formatter.locals_without_parens()
+       ) do
+      # Macro.to_string formats some locals without parens
+      # notable case is Phoenix.Endpoint.config/2 callback
+      replacement = :__elixir_sense_replace_me__
+
+      Macro.to_string({replacement, meta, args})
+      |> String.replace(Atom.to_string(replacement), Atom.to_string(name))
+    else
+      Macro.to_string({name, meta, args})
+    end
+  end
+
+  def to_string_with_parens(ast) do
+    Macro.to_string(ast)
   end
 
   defp strip_types(args, arity) do

lib/elixir_sense/core/type_info.ex

@@ -456,7 +456,7 @@ defmodule ElixirSense.Core.TypeInfo do
   end
 
   def type_str(type) do
-    typespec_to_quoted(type) |> Macro.to_string()
+    typespec_to_quoted(type) |> Introspection.to_string_with_parens()
   end
 
   defp extract_list_type_spec_options(list_type_specs) do

lib/elixir_sense/providers/suggestion/reducers/struct.ex

@@ -130,7 +130,7 @@ defmodule ElixirSense.Providers.Suggestion.Reducers.Struct do
             end
 
           some ->
-            Macro.to_string(some)
+            Introspection.to_string_with_parens(some)
         end
 
       %{