Error running transpose tests

When running the tests for the `transpose` exercise with the following code:

```kotlin
object Transpose {

fun transpose(input: List): List {
val longestLength = input.map { it.length }.max()
return List(longestLength) { index ->
input
.map { it.padEnd(longestLength) }
.map { it[index] }
.joinToString(separator = "")
}.map { it.trimEnd() }
}
}
```

The test runner fails with:

```
Picked up JAVA_TOOL_OPTIONS: -Xss128m -Xms256m -Xmx2G -XX:+UseG1GC
Exception in thread "main" java.lang.NullPointerException: attribute(...) must not be null
at utils.junit.ParserKt.get(parser.kt:97)
at utils.junit.ParserKt.asError(parser.kt:51)
at utils.junit.ParserKt.asTestCase(parser.kt:37)
at utils.junit.ParserKt.asTestSuit(parser.kt:26)
at utils.junit.ParserKt.parseJUnit4Results(parser.kt:14)
at exercism.kotlin.autotests.executor.ExecutorKt.buildExecutionResult(executor.kt:101)
at exercism.kotlin.autotests.executor.ExecutorKt.executor(executor.kt:12)
at exercism.kotlin.autotests.runner.MainKt$main$result$1.invoke(main.kt:28)
at exercism.kotlin.autotests.runner.MainKt$main$result$1.invoke(main.kt:28)
at exercism.kotlin.autotests.executor.EnvironmentKt.executeOnEnvironment(environment.kt:16)
at exercism.kotlin.autotests.runner.MainKt.main(main.kt:28)

```

@ErwinOlie Do you have any idea?