How to use Expanded with Future - flutter

Question

Part of my code is as follows:
Expanded(
flex: 13,
child: Container(
padding: EdgeInsets.all(2),
color: Colors.black12,
child: FutureBuilder(
future: getCompromissos(),
builder: (context, snapshot) {
if (compromissosFiltrados != null && compromissosFiltrados.compromissos.length > 0) {
return ListView.builder(
controller: ScrollController(),
shrinkWrap: true,
scrollDirection: Axis.horizontal,
itemCount: compromissosFiltrados.compromissos.length,
itemBuilder: (context, index) {
return CompromissoCard(
indice: index,
title: compromissosFiltrados.compromissos[index].nome,
icon: new Icon(icons[0], size: 24.0, color: Colors.green));
},
);
} else {
return Container();
}
},
),
),
),
Sometimes getCompromissos() does not return any item and I have that empty space in my app.
I would like Expanded occupied all the space when there are nothing to show, like this:
In the lower part Expanded( flex: 0 is working because contents of that widget don't come from the web.
But in this widget if I use flex : 0 and there's not item, it's ok, but if there are items then I have errors like this:
RenderBox was not laid out: RenderRepaintBoundary#6c79b
relayoutBoundary=up6 NEEDS-PAINT
'package:flutter/src/rendering/box.dart': Failed assertion: line 1694
pos 12: 'hasSize'
In case you need that part of CompromissoCard
return new Container(
color: Colors.white12,
child: new Card(
child: Container(
color: Colors.white30,
padding: new EdgeInsets.only(left: 5, top: 5, bottom: 5, right: 10),
child: new Row(children: <Widget>[
Column(children: <Widget>[
SizedBox(height: 15),
Column(children: <Widget>[new Image.asset("assets/images/meeting.png")])
]),
Column(children: <Widget>[
Row(
children: <Widget>[
Column(children: <Widget>[
SizedBox(
height: 15,
),
Text("13:00 - 14:00", style: TextStyle(color: Colors.black38, fontSize: 16)),
SizedBox(
height: 5,
),
Text(this.title, style: TextStyle(color: Colors.black, fontSize: 16, fontWeight: FontWeight.w300))
]),
],
),
])
]),
),
));
I can't figure out how to do this.
Someone could help me? Thanks in an advance.