Improve error reporting

[bamboo]

No description provided.

[tadaskay]

I guess this is related: when you apply from a non-existing file, it gives you a NPE rather than a proper message:
applyFrom("asdf.gradle.kts") ->

Caused by: kotlin.KotlinNullPointerException
        at org.gradle.script.lang.kotlin.provider.KotlinBuildScriptCompiler.<init>(KotlinBuildScriptCompiler.kt:49)
        at org.gradle.script.lang.kotlin.provider.KotlinScriptPluginFactory.compilerFor(KotlinScriptPluginFactory.kt:55)
        at org.gradle.script.lang.kotlin.provider.KotlinScriptPluginFactory.compile(KotlinScriptPluginFactory.kt:45)
        at org.gradle.script.lang.kotlin.provider.KotlinScriptPluginFactory.create(KotlinScriptPluginFactory.kt:38)
        at org.gradle.configuration.ScriptPluginFactorySelector.create(ScriptPluginFactorySelector.java:55)
        at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction.applyScript(DefaultObjectConfigurationAction.java:100)
        at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction.access$000(DefaultObjectConfigurationAction.java:36)
        at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction$1.run(DefaultObjectConfigurationAction.java:62)
        at org.gradle.api.internal.plugins.DefaultObjectConfigurationAction.execute(DefaultObjectConfigurationAction.java:136)
        at org.gradle.api.internal.project.AbstractPluginAware.apply(AbstractPluginAware.java:38)
        at Build_gradle.<init>(build.gradle.kts:17)

[bamboo]

It is. Thanks for the report @tadaskay!