From d212c2f21ae5043a4b386ed496ad5fa0776a89d6 Mon Sep 17 00:00:00 2001
From: Maxime Mangel <maxime.shadaen@protonmail.com>
Date: Wed, 16 Aug 2023 21:30:27 +0200
Subject: [PATCH] Don't ignore error when loading plugin

Fix #3441
---
 src/Fable.Cli/RELEASE_NOTES.md |  1 +
 src/Fable.Transforms/State.fs  | 37 +++++++++++++++++++++++++---------
 2 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/src/Fable.Cli/RELEASE_NOTES.md b/src/Fable.Cli/RELEASE_NOTES.md
index 03347b1427..09952bd709 100644
--- a/src/Fable.Cli/RELEASE_NOTES.md
+++ b/src/Fable.Cli/RELEASE_NOTES.md
@@ -8,6 +8,7 @@
 * Fix #3464: Invalidate cache when the target language changes
 * Always delete the `fable_modules` folder when the cache is invalidated
 * Remove `--typescript` options support, use `--lang <target>` instead
+* Fix #3441: Don't ignore error when loading plugin
 
 ### 4.1.4
 
diff --git a/src/Fable.Transforms/State.fs b/src/Fable.Transforms/State.fs
index e3874a7d14..5c2e0ec7fd 100644
--- a/src/Fable.Transforms/State.fs
+++ b/src/Fable.Transforms/State.fs
@@ -5,6 +5,7 @@ open Fable.AST
 open System.Collections.Concurrent
 open System.Collections.Generic
 open FSharp.Compiler.Symbols
+open System
 
 type PluginRef =
     { DllPath: string
@@ -26,16 +27,32 @@ type Assemblies(getPlugin, fsharpAssemblies: FSharpAssembly list) =
                 if Compiler.CoreAssemblyNames.Contains(asmName) then
                     coreAssemblies.Add(asmName, asm)
                 else
-                    try
-                        let scanForPlugins =
-                            asm.Contents.Attributes |> Seq.exists (fun attr ->
-                                attr.AttributeType.TryFullName = Some "Fable.ScanForPluginsAttribute")
-                        if scanForPlugins then
-                           for e in asm.Contents.Entities do
-                                   if e.IsAttributeType && FSharp2Fable.Util.inherits e "Fable.PluginAttribute" then
-                                       let plugin = getPlugin { DllPath = path; TypeFullName = e.FullName }
-                                       plugins.Add(FSharp2Fable.FsEnt.Ref e, plugin)
-                    with _ -> ()
+                    let scanForPlugins =
+                        asm.Contents.Attributes |> Seq.exists (fun attr ->
+                            attr.AttributeType.TryFullName = Some "Fable.ScanForPluginsAttribute")
+                    if scanForPlugins then
+                        for e in asm.Contents.Entities do
+                            if e.IsAttributeType && FSharp2Fable.Util.inherits e "Fable.PluginAttribute" then
+                                try
+                                    let plugin = getPlugin { DllPath = path; TypeFullName = e.FullName }
+                                    plugins.Add(FSharp2Fable.FsEnt.Ref e, plugin)
+                                with ex ->
+                                    let errorMessage =
+                                        [
+                                            $"Error while loading plugin: {e.FullName}"
+                                            ""
+                                            "This error often happens if you are trying to use a plugin that is not compatible with the current version of Fable."
+                                            ""
+                                            "If you see this error please open an issue at https://github.com/fable-compiler/Fable/"
+                                            "so we can check if we can improve the plugin detection mechanism."
+                                        ]
+                                        |> String.concat "\n"
+
+                                    Console.ForegroundColor <- ConsoleColor.DarkRed
+                                    Console.Error.WriteLine(errorMessage)
+                                    Console.ResetColor()
+                                    raise ex
+
                     assemblies.Add(path, asm)
             | None -> ()