[Gradle, JS] Not run task if root package.json doesn't exist

#KT-34832 fixed

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/targets/js/npm/tasks/KotlinNpmInstallTask.kt

@@ -13,6 +13,10 @@ import java.io.File
 open class KotlinNpmInstallTask : DefaultTask() {
     init {
         check(project == project.rootProject)
+
+        onlyIf {
+            rootPackageJson.exists()
+        }
     }
 
     private val nodeJs get() = NodeJsRootPlugin.apply(project.rootProject)