Respect withFrozenCallStack used by callers of send

Fixes regression introduced by b92dc37.

effectful-core/CHANGELOG.md

@@ -1,6 +1,7 @@
 # effectful-core-2.3.1.0 (????-??-??)
 * Remove inaccurate information from the `Show` instance of `ErrorWrapper`.
 * Add `Effectful.Provider.List`, generalization of `Effectful.Provider`.
+* Respect `withFrozenCallStack` used by callers of `send`.
 
 # effectful-core-2.3.0.1 (2023-11-13)
 * Prevent internal functions from appending call stack frames to handlers.

effectful-core/src/Effectful/Internal/Utils.hs

@@ -186,5 +186,5 @@ newUnique = Unique <$> newByteArray 0
 
 thawCallStack :: CallStack -> CallStack
 thawCallStack = \case
-  FreezeCallStack cs -> thawCallStack cs
+  FreezeCallStack cs -> cs
   cs -> cs

effectful/tests/ErrorTests.hs

@@ -6,10 +6,12 @@ import Test.Tasty.HUnit
 import Effectful
 import Effectful.Dispatch.Dynamic
 import Effectful.Error.Static
+import qualified Effectful.Error.Dynamic as D
 
 errorTests :: TestTree
 errorTests = testGroup "Error"
   [ testCase "different handlers are independent" test_independentHandlers
+  , testCase "call stack of dynamic throwError doesn't show internal details" test_dynamicThrowErrorCallStack
   ]
 
 test_independentHandlers :: Assertion
@@ -21,6 +23,13 @@ test_independentHandlers = runEff $ do
       "outerThrow" == fst (last $ getCallStack cs)
     Right _ -> assertFailure "error caught by the wrong (inner) handler"
 
+test_dynamicThrowErrorCallStack :: Assertion
+test_dynamicThrowErrorCallStack = do
+  Left (cs, ()) <- runEff . D.runError @() $ D.throwError ()
+  case getCallStack cs of
+    [("throwError", _)] -> pure ()
+    _ -> assertFailure $ "invalid call stack: " ++ prettyCallStack cs
+
 ----------------------------------------
 -- Helpers