Hi,

I wanted to build Railcraft for Minecraft 1.12.2. So I downloaded the code, unziped, and ran gradlew.
Immediately I get this error:

FAILURE: Build failed with an exception.

• Where:
  Build file '/home/someguy/Downloads/Railcraft/Railcraft-mc-1.12.2/version/build.gradle' line: 6

• What went wrong:
  A problem occurred evaluating project ':version'.

Cannot get property 'version_minecraft' on extra properties extension as it does not exist

• Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

• Get more help at https://help.gradle.org

BUILD FAILED in 0s

Just let me know if there are any more information that you need :)
I'm using Kubuntu 18.04 btw.

Have a great day!
Kind regards!

Import submodules and reload Gradle. See what happens then. If it still fails redo setuoDecompWorkdpace

How to do this?

Read a "Building" section in a README.

git submodule init
git submodule update

Get on discord if you need additional help.

never download zip in the future