From 00b09bca6ef520663d9ce9a3348af7c367b5ceee Mon Sep 17 00:00:00 2001
From: Simon Vandel Sillesen <simon.vandel@gmail.com>
Date: Fri, 9 Dec 2022 10:37:10 +0000
Subject: [PATCH] fix(napi): better error message for `#[napi(catch_unwind)]`
 (#1383)

Before, the JS error would only have `Any { .. }`
---
 crates/backend/src/codegen/fn.rs | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/crates/backend/src/codegen/fn.rs b/crates/backend/src/codegen/fn.rs
index 7ccff0dd..c724b8d9 100644
--- a/crates/backend/src/codegen/fn.rs
+++ b/crates/backend/src/codegen/fn.rs
@@ -140,7 +140,18 @@ impl TryToTokens for NapiFn {
       quote! {
         {
           std::panic::catch_unwind(|| { #function_call })
-            .map_err(|e| napi::Error::new(napi::Status::GenericFailure, format!("{:?}", e)))
+            .map_err(|e| {
+              let message = {
+                if let Some(string) = e.downcast_ref::<String>() {
+                  string.clone()
+                } else if let Some(string) = e.downcast_ref::<&str>() {
+                  string.to_string()
+                } else {
+                  format!("panic from Rust code: {:?}", e)
+                }
+              };
+              napi::Error::new(napi::Status::GenericFailure, message)
+            })
             .and_then(|r| r)
         }
       }