Postpone execution code after wait method, since it's executed in a native callback which can't be async. When the code contains async calls, compiler produces error.

classlib/src/main/java/org/teavm/classlib/java/lang/TObject.java

@@ -344,9 +344,11 @@ public class TObject {
 
         @Override
         public void onTimer() {
-            if (!expired()) {
-                run();
-            }
+            Platform.postpone(() -> {
+                if (!expired()) {
+                    run();
+                }
+            });
         }
 
         @Override