BridgeJS: fix codegen for async + throws exported methods

The render method handled isAsync and isThrows as mutually exclusive
branches, so methods that were both async and throws only got the
JSPromise.async wrapper without the explicit throws(JSException) type
annotation on the closure. This caused the Swift compiler to infer
throws(any Error) instead of throws(JSException), producing a build
error.

Add a new branch for the combined case that explicitly annotates the
closure with `() async throws(JSException) [-> JSValue] in`.

Made-with: Cursor

Author: Ryan-Sheehan

Plugins/BridgeJS/Sources/BridgeJSCore/ExportSwift.swift

@@ -319,8 +319,19 @@ public class ExportSwift {
         func render(abiName: String) -> DeclSyntax {
             let body: CodeBlockItemListSyntax
             if effects.isAsync {
+                // Explicit closure type annotation needed when throws is present
+                // so Swift infers throws(JSException) instead of throws(any Error)
+                // See: https://github.com/swiftlang/swift/issues/76165
+                let closureHead: String
+                if effects.isThrows {
+                    let hasReturn = self.body.contains { $0.description.contains("return ") }
+                    let ret = hasReturn ? " -> JSValue" : ""
+                    closureHead = " () async throws(JSException)\(ret) in"
+                } else {
+                    closureHead = ""
+                }
                 body = """
-                    let ret = JSPromise.async {
+                    let ret = JSPromise.async {\(raw: closureHead)
                         \(CodeBlockItemListSyntax(self.body))
                     }.jsObject
                     return ret.bridgeJSLowerReturn()