Avoid alloc in wrapped func when returning error

src/func.zig

@@ -135,11 +135,8 @@ pub const Func = extern struct {
                         // If function returns an ErrorUnion, convert it to
                         // its payload, or return a trap if an error occurred.
                         const func_results = if (@typeInfo(@TypeOf(func_results_maybe_error)) == .ErrorUnion)
-                            func_results_maybe_error catch |err| {
-                                const fmt = "Error '{s}' occurred in host code";
-                                const msg = std.fmt.allocPrintZ(c_alloc, fmt, .{@errorName(err)});
-                                return Trap.init(msg catch "Error occurred in host code");
-                            }
+                            func_results_maybe_error catch |err|
+                                return Trap.init(@errorName(err))
                         else
                             func_results_maybe_error;