More informative error message

tessi · Apr 3, 2024 · 42f4e3d · 42f4e3d
1 parent f651ad4
commit 42f4e3d
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Showing 2 changed files with 10 additions and 2 deletions.
diff --git a/native/wasmex/src/instance.rs b/native/wasmex/src/instance.rs
@@ -148,8 +148,13 @@ pub fn set_global_value(
 
     let global_type = global.ty(&store_or_caller).content().clone();
 
-    let new_value = decode_term_as_wasm_value(global_type, new_value)
-        .ok_or_else(|| rustler::Error::Term(Box::new("Cannot convert to a WebAssembly value.")))?;
+    let new_value = decode_term_as_wasm_value(global_type.clone(), new_value).ok_or_else(|| {
+        rustler::Error::Term(Box::new(format!(
+            "Cannot convert to a WebAssembly {:?} value. Given `{:?}`.",
+            global_type,
+            PrintableTermType::PrintTerm(new_value.get_type())
+        )))
+    })?;
 
     let val: Val = match new_value {
         WasmValue::I32(value) => value.into(),

diff --git a/test/wasmex/instance_test.exs b/test/wasmex/instance_test.exs
@@ -227,6 +227,9 @@ defmodule Wasmex.InstanceTest do
       assert {:error, "Could not set global: immutable global cannot be set"} =
                Wasmex.Instance.set_global_value(store, instance, "meaning_of_life", 0)
 
+      assert {:error, "Cannot convert to a WebAssembly I32 value. Given `Atom`."} =
+               Wasmex.Instance.set_global_value(store, instance, "count_32", :abc)
+
       assert :ok = Wasmex.Instance.set_global_value(store, instance, "count_32", 99)
       assert {:ok, 99} = Wasmex.Instance.get_global_value(store, instance, "count_32")