Fixed sized button and expanded textfield inside Row Flutter

I want to develop a UI just like Postman Desktop App. But When I add a text field and fix the sized button in a row it gives an error RenderFlex children have non-zero flex but incoming width constraints are unbounded. But I don’t want to give a fixed size to the text field through MediaQuery. As you can see in this video (Demo UI) Postman text field size is fixed when the screen size decrease it shows a horizontal scrollbar. I want the same behavior. Here is the code.

      body: SingleChildScrollView(
        scrollDirection: Axis.horizontal,
        child: SizedBox(
          height: MediaQuery.of(context).size.height,
          child: Row(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              SingleChildScrollView(
                child: Container(
                  height: MediaQuery.of(context).size.height,
                  width: 300,
                  decoration:
                      BoxDecoration(border: Border.all(color: Colors.yellow)),
                  child: Column(
                    mainAxisAlignment: MainAxisAlignment.start,
                    children: [
                      Container(
                        decoration: BoxDecoration(
                            border: Border.all(color: Colors.red)),
                        child: Image.network(
                          ImageURL,
                          fit: BoxFit.fitWidth,
                        ),
                      ),
                    ],
                  ),
                ),
              ),
              SizedBox(
                child: Column(
                  children: [
                    Row(
                      children: <Widget>[
                        const Expanded(child: TextField()),
                        DarkButton("Save", () {}),
                      ],
                    ),
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );