Fix "No such variable" in typed output block with job arrays

modules/nextflow/src/main/groovy/nextflow/processor/TaskArrayRun.groovy

@@ -58,4 +58,9 @@ class TaskArrayRun extends TaskRun {
         return true
     }
 
+    @Override
+    List<String> getOutputFilesNames() {
+        return Collections.<String>emptyList()
+    }
+
 }

modules/nextflow/src/test/groovy/nextflow/processor/TaskArrayRunTest.groovy

@@ -20,6 +20,7 @@ import nextflow.Session
 import nextflow.container.resolver.ContainerInfo
 import nextflow.executor.Executor
 import nextflow.executor.TaskArrayExecutor
+import nextflow.script.ProcessConfigV2
 import spock.lang.Specification
 /**
  *
@@ -52,4 +53,19 @@ class TaskArrayRunTest extends Specification {
         task.isArray()
     }
 
+    def 'should not stage output files because it is only a child task launcher' () {
+        given: 'a typed process'
+        def config = Mock(ProcessConfigV2)
+        def processor = Mock(TaskProcessor) { getConfig() >> config }
+        and: 'an array task whose context has no input variables bound, like the real array parent'
+        def task = new TaskArrayRun(processor: processor, context: Mock(TaskContext))
+
+        when:
+        def names = task.getOutputFilesNames()
+
+        then: 'no output files are returned and the typed output declarations are never evaluated'
+        names == []
+        0 * config.getOutputs()
+    }
+
 }