Fix pick_value all_non_null empty result + parameter default unwrap.

- all_non_null mode now produces empty collection when all inputs
  are null instead of erroring. Matches expected semantics where
  filtering nulls can yield zero results.
- Fix _ensure_input_step_outputs_populated to unwrap {"src": "json",
  "value": X} parameter defaults, matching InputParameterModule's
  get_input_value() unwrap logic. Pre-populated values now consistent
  with what execute() produces.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/galaxy/workflow/modules.py

@@ -2085,13 +2085,8 @@ class PickValueModule(WorkflowModule):
             output = non_null[0]
 
         elif mode == "all_non_null":
-            if not non_null:
-                raise FailWorkflowEvaluation(
-                    why=InvocationFailureExpressionEvaluationFailed(
-                        reason=FailureReason.expression_evaluation_failed,
-                        workflow_step_id=step.id,
-                    )
-                )
+            # CWL spec: all_non_null returns list of non-null values,
+            # which may be empty if all inputs are null.
             output = self._create_collection_from_list(trans, invocation_step, non_null)
 
         else:

lib/galaxy/workflow/run.py

@@ -724,7 +724,13 @@ class WorkflowProgress:
         # Determine output value from inputs_by_step_id or default
         outputs = {}
         if step.id not in self.inputs_by_step_id:
-            outputs["output"] = step.get_input_default_value(NO_REPLACEMENT)
+            default_value = step.get_input_default_value(NO_REPLACEMENT)
+            # For parameter_input steps, unwrap {"src": "json", "value": X}
+            # dicts to just X — matching the unwrap logic in
+            # InputParameterModule.get_input_value().
+            if step.type == "parameter_input" and isinstance(default_value, dict):
+                default_value = default_value.get("value", default_value)
+            outputs["output"] = default_value
         else:
             outputs["output"] = self.inputs_by_step_id[step.id]