Improve log outputs in CI

* This prevents the "Output full log" step from failing with
  file-not-found if the 'success' log file is absent.

* It also shows the 'failure' log file if present, for easier
  debugging.

.github/workflows/run_batch_script.yml

@@ -53,12 +53,19 @@ jobs:
     - name: Output full log for sanity checking
       run: |
         cd "${{ github.event.repository.name }}/multi_subject/output/log"
-        cat process_data_sub-01.log
+        for logfile in process_data_sub-01.log err.process_data_sub-01.log; do
+            if [[ -e "${logfile}" ]]; then
+                echo "=== Contents of ${logfile} ==="
+                cat "${logfile}"
+            else
+                echo "=== No file ${logfile} ==="
+            fi
+        done
 
     - name: Check that script executed without error
       run: |
         cd "${{ github.event.repository.name }}/multi_subject/output/log"
         [ "$(compgen -G "process_data_sub-0*.log")" ]        # Log files should exist
         [ ! "$(compgen -G "err.process_data_sub-0*.log")" ]  # Error files should NOT exist
         grep -iF "warning" process_data_sub-01.log
-        grep -iF "error" process_data_sub-01.log
+        grep -iF "error" process_data_sub-01.log