Ignore async_stack_size if async_support is disabled (#6771)

Fixes an issue where max_wasm_stack was being validated against
async_stack_size when async_support was disabled, discussed in #6762.

crates/wasmtime/src/config.rs

@@ -1498,7 +1498,7 @@ impl Config {
             bail!("feature 'threads' requires 'bulk_memory' to be enabled");
         }
         #[cfg(feature = "async")]
-        if self.max_wasm_stack > self.async_stack_size {
+        if self.async_support && self.max_wasm_stack > self.async_stack_size {
             bail!("max_wasm_stack size cannot exceed the async_stack_size");
         }
         if self.max_wasm_stack == 0 {

tests/all/traps.rs

@@ -1643,3 +1643,13 @@ fn same_module_multiple_stores() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn async_stack_size_ignored_if_disabled() -> Result<()> {
+    let mut config = Config::new();
+    config.async_support(false);
+    config.max_wasm_stack(8 << 20);
+    Engine::new(&config)?;
+
+    Ok(())
+}