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

[jorgee]

Problem

Closes #7215.

A typed (v2) process that references an input variable in an output file pattern fails with ERROR ~ No such variable: <input> when job array batching is active, e.g.:

nextflow.enable.types = true

process getSce {
    input:
    localFile: Path

    output:
    sce: Path = file("${localFile.baseName}_sce.rds")

    script:
    """
    touch ${localFile.baseName}_sce.rds
    """
}

• ✗ Fails: -profile slurm --arraySize 2 (array enabled)
• ✓ Works: -profile slurm --arraySize 1 (no array)
• ✓ Works: -profile local

Root cause

When array > 1, TaskArrayCollector.createTaskArray() builds a parent TaskArrayRun with a fresh, empty task context — it is only a launcher that dispatches the child tasks and stages no outputs of its own.

TaskBean calls getOutputFilesNames() for every task, including the array parent. For typed (v2) processes, getOutputFilesNamesV2() evaluates the process-level declared output patterns against the task context. The parent's context has no inputs bound, so resolving file("${localFile.baseName}_sce.rds") throws No such variable: localFile.

DSL v1 was unaffected because getOutputFilesNamesV1() reads the task's instance-resolved outputs, which are empty for the parent.

Fix

Override getOutputFilesNames() in TaskArrayRun to return an empty list. The array parent stages no outputs of its own (children unstage their own outputs); this matches the effective v1 behaviour and avoids evaluating output declarations against the parent's empty context.

Testing

• New regression test in TaskArrayRunTest — verified it fails without the fix and passes with it.
• Reproduced the original issue end-to-end on a local SLURM (docker) cluster and confirmed all three scenarios (slurm arraySize=2, slurm arraySize=1, local) now succeed, with child output files correctly produced and staged.

🤖 Generated with Claude Code

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