Changed raise to calling Reraise() extension method to preserve the call stack

Author: xperiandri

src/FSharp.Data.GraphQL.Shared/AsyncVal.fs

@@ -41,7 +41,7 @@ module AsyncVal =
         match x with
         | Value v -> v
         | Async a -> a |> Async.RunSynchronously
-        | Failure f -> raise f
+        | Failure f -> f.Reraise()
 
     /// Create new AsyncVal from Async computation.
     let inline ofAsync (a: Async<'T>) = Async(a)
@@ -54,7 +54,7 @@ module AsyncVal =
         match x with
         | Value v -> async.Return v
         | Async a -> a
-        | Failure f -> async.Return (raise f)
+        | Failure f -> async.Return (f.Reraise())
 
     /// Returns an empty AsyncVal with immediatelly executed value.
     let inline empty<'T> : AsyncVal<'T> = AsyncVal<'T>.Zero
@@ -111,7 +111,7 @@ module AsyncVal =
                 match bound with
                 | Value v -> return v
                 | Async a -> return! a
-                | Failure f -> return raise f
+                | Failure f -> return f.Reraise()
             })
         | Failure f -> Failure(f)
 
@@ -133,7 +133,7 @@ module AsyncVal =
                         let! r = a
                         results.[i] <- r
                     | Failure f ->
-                        results.[i] <- raise f
+                        results.[i] <- f.Reraise()
                 return results })
         else Value (values |> Array.map (fun (Value v) -> v))
 
@@ -156,7 +156,7 @@ module AsyncVal =
                     indexes.Add i
                     continuations.Add a
                 | Failure f ->
-                    results.[i] <- raise f
+                    results.[i] <- f.Reraise()
             if indexes.Count = 0
             then Value(results)
             else Async(async {
@@ -193,7 +193,7 @@ type AsyncValBuilder () =
             match bound with
             | Value v -> return v
             | Async a -> return! a
-            | Failure f -> return raise f })
+            | Failure f -> return f.Reraise() })
 
 
 [<AutoOpen>]

src/FSharp.Data.GraphQL.Shared/Exception.fs

@@ -0,0 +1,16 @@
+[<AutoOpen>]
+[<CompilationRepresentation (CompilationRepresentationFlags.ModuleSuffix)>]
+module System.Exception
+
+open System
+open System.Diagnostics
+open System.Runtime.ExceptionServices
+
+// Useful for reraising exceptions under an async {...} and task {...} contexts
+// See this for more details: https://github.com/fsharp/fslang-suggestions/issues/660
+type internal Exception with
+
+    [<DebuggerHidden>]
+    member __.Reraise () =
+        (ExceptionDispatchInfo.Capture __).Throw ()
+        Unchecked.defaultof<_>

src/FSharp.Data.GraphQL.Shared/FSharp.Data.GraphQL.Shared.fsproj

@@ -49,6 +49,7 @@
     <Compile Include="Helpers\Reflection.fs" />
     <Compile Include="Helpers\MemoryCache.fs" />
     <Compile Include="Errors.fs" />
+    <Compile Include="Exception.fs" />
     <Compile Include="ValidationTypes.fs" />
     <Compile Include="AsyncVal.fs" />
     <Compile Include="Ast.fs" />

tests/FSharp.Data.GraphQL.Tests/Helpers.fs

@@ -146,7 +146,7 @@ type TestObserver<'T>(obs : IObservable<'T>, ?onReceived : TestObserver<'T> -> '
         member _.OnCompleted() =
             isCompleted <- true
             mre.Set() |> ignore
-        member _.OnError(error) = raise error
+        member _.OnError(error) = error.Reraise()
         member _.OnNext(value) =
             received.Add(value)
             onReceived |> Option.iter (fun evt -> evt this value)