Suppress warning for "inferred to have type '()',"

[sidepelican]

This is a minor improvement to silence a compiler warning in the generated code like below.

/Users/iceman/github/swift-java/Samples/SwiftJavaExtractJNISampleApp/.build/plugins/outputs/swiftjavaextractjnisampleapp/MySwiftLibrary/destination/JExtractSwiftPlugin/Sources/MySwiftLibraryModule+SwiftJava.swift:864:13: warning: constant 'swiftResult$' inferred to have type '()', which may be unexpected
 862 |       } // printTaskBody(printer:) @ JExtractSwiftLib/JNISwift2JavaGenerator+NativeTranslation.swift:1151
 863 |       do {
 864 |         let swiftResult$ = try await MySwiftLibrary.asyncThrows()
     |             |- warning: constant 'swiftResult$' inferred to have type '()', which may be unexpected
     |             `- note: add an explicit type annotation to silence this warning
 865 |         environment = try! JavaVirtualMachine.shared().environment()
 866 |         _ = environment.interface.CallBooleanMethodA(environment, globalFuture, _JNIMethodIDCache.CompletableFuture.complete, [jvalue(l: nil)])

Since the generator already checks for .isVoid at this location, I have slightly adjusted the logic to avoid assigning the result.

[ktoso]

no need to move the environment initialization?

[sidepelican]

The only difference is whether we write the if statement twice or not.
I was okay with a single line of duplication, but we could also write the if statement twice if preferred.

[ktoso]

I mean, you can keep the printer.print("environment = try! JavaVirtualMachine.shared().environment()") before the if entirely so we don't duplicate the string in both branches

[sidepelican]

I thought it would be better not to change the timing of fetching environment as it might span across a suspention point (await).

[ktoso]

Hmm... let's go with this, though arguably before might be safer tbh...