minor fixes

com.unity.uiwidgets/Runtime/async/future.cs

                     future.then((object value) => {
                         remaining--;
                         if (values != null) {
-                            values.Insert(pos, (T)value);
+                            values[pos] = (T)value;
                             if (remaining == 0) {
                                 result._completeWithValue(values);
                             }
                     return value(FutureOr.value(new List<T>()));
                 }
 
-                values = new List<T>(remaining);
+                values = new List<T>(new T[remaining]);
             }
             catch (Exception e) {
                 // The error must have been thrown while iterating over the futures

com.unity.uiwidgets/Runtime/foundation/assertions.cs

                     details.toDiagnosticsNode(style: DiagnosticsTreeStyle.error)).TrimEnd(), details.exception);   
             }
             
-            D.logError($"Another exception was thrown: ${details.summary}");
+            D.logError($"Another exception was thrown: ${details.summary}", details.exception);
 
             _errorCount += 1;
         }

com.unity.uiwidgets/Runtime/foundation/debug.cs

         public AssertionError(string message) : base(message: message) {
         }
 
-        public AssertionError(string message, Exception innerException = null) : base(message: message) {
+        public AssertionError(string message, Exception innerException) : base(message: message) {
             this.innerException = innerException;
         }