Failing master branch - RenderFlex overflowing

[0xSSDD]

Checking out the master branch at it's latest commit does not work:

* What went wrong:
A problem occurred evaluating project ':cloud_firestore'.
> Could not find method platform() for arguments [com.google.firebase:firebase-bom:26.2.0] on object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler.

Also I have followed along on your platform, but yet at the end I am getting this error. In topics.dart

======== Exception caught by rendering library =====================================================
The following assertion was thrown during layout:
A RenderFlex overflowed by 99854 pixels on the bottom.

The relevant error-causing widget was: 
  Column file:///home/arpan/Documents/School/sem4/mobile-apps/quizapp/lib/screens/topics.dart:65:20
The overflowing RenderFlex has an orientation of Axis.vertical.
The edge of the RenderFlex that is overflowing has been marked in the rendering with a yellow and black striped pattern. This is usually caused by the contents being too big for the RenderFlex.

Consider applying a flex factor (e.g. using an Expanded widget) to force the children of the RenderFlex to fit within the available space instead of being sized to their natural size.
This is considered an error condition because it indicates that there is content that cannot be seen. If the content is legitimately bigger than the available space, consider clipping it with a ClipRect widget before putting it in the flex, or using a scrollable container rather than a Flex, like a ListView.

The specific RenderFlex in question is: RenderFlex#b685a OVERFLOWING
...  parentData: <none> (can use size)
...  constraints: BoxConstraints(w=172.7, h=172.7)
...  size: Size(172.7, 172.7)
...  direction: vertical
...  mainAxisAlignment: spaceBetween
...  mainAxisSize: max
...  crossAxisAlignment: start
...  textDirection: ltr
...  verticalDirection: down

Regards