Fix NPE in build script

Author: AB-xdev

build.gradle

@@ -98,6 +98,6 @@ tasks {
         // Specify pre-release label to publish the plugin in a custom Release Channel automatically. Read more:
         // https://plugins.jetbrains.com/docs/intellij/deployment.html#specifying-a-release-channel
         channels = properties("pluginVersion")
-                .map { [(it.split('-')[1] ?: "default").split('\\.').find { true }.toLowerCase()] }
+                .map { [((it.split('-') as List)[1] ?: "default").split('\\.').find { true }.toLowerCase()] }
     }
 }