Bubbler / Bubbler4 block crashes during graph assembly when input vector has one value instead of two

[K0ati]

Description

I’m seeing a simulation failure when loading/running a minimal .pvm case that includes a tritium bubbler block.
When running a minimal .pvm case with a tritium Bubbler block, the simulation fails during initialization.

SIMULATION ERROR

Traceback (most recent call last):
  File "<exec>", line 37, in <module>
  File "/lib/python3.12/site-packages/pathsim/simulation.py", line 271, in __init__
    self._assemble_graph()
  File "/lib/python3.12/site-packages/pathsim/simulation.py", line 695, in _assemble_graph
    self.graph = Graph(self.blocks, self.connections)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim/utils/graph.py", line 73, in __init__
    self._build_all_maps()
  File "/lib/python3.12/site-packages/pathsim/utils/graph.py", line 147, in _build_all_maps
    if len(blk) > 0:
       ^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim/blocks/dynsys.py", line 97, in __len__
    has_passthrough = np.any(self.op_alg.jac_u(x, u, 0.0))
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim/optim/operator.py", line 380, in jac_u
    return num_jac(func_u, u)
           ^^^^^^^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim/optim/numerical.py", line 52, in num_jac
    [(func(x + hv) - func(x - hv)) / h
     ^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim/optim/operator.py", line 378, in func_u
    return self._func(x, _u, t)
           ^^^^^^^^^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim_chem/tritium/bubbler.py", line 146, in _fn_a
    sol, ins = u
    ^^^^^^^^
ValueError: not enough values to unpack (expected 2, got 1)


Streaming simulation failed: Traceback (most recent call last):
  File "/lib/python312.zip/_pyodide/_base.py", line 596, in eval_code_async
    await CodeRunner(
  File "/lib/python312.zip/_pyodide/_base.py", line 410, in run_async
    coroutine = eval(self.code, globals, locals)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<exec>", line 37, in <module>
  File "/lib/python3.12/site-packages/pathsim/simulation.py", line 271, in __init__
    self._assemble_graph()
  File "/lib/python3.12/site-packages/pathsim/simulation.py", line 695, in _assemble_graph
    self.graph = Graph(self.blocks, self.connections)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim/utils/graph.py", line 73, in __init__
    self._build_all_maps()
  File "/lib/python3.12/site-packages/pathsim/utils/graph.py", line 147, in _build_all_maps
    if len(blk) > 0:
       ^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim/blocks/dynsys.py", line 97, in __len__
    has_passthrough = np.any(self.op_alg.jac_u(x, u, 0.0))
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim/optim/operator.py", line 380, in jac_u
    return num_jac(func_u, u)
           ^^^^^^^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim/optim/numerical.py", line 52, in num_jac
    [(func(x + hv) - func(x - hv)) / h
     ^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim/optim/operator.py", line 378, in func_u
    return self._func(x, _u, t)
           ^^^^^^^^^^^^^^^^^^^^
  File "/lib/python3.12/site-packages/pathsim_chem/tritium/bubbler.py", line 146, in _fn_a
    sol, ins = u
    ^^^^^^^^
ValueError: not enough values to unpack (expected 2, got 1)

NoneType: None

Essentially,

Bubbler._fn_a() expects two inputs, but during graph assembly / passthrough detection, PathSim calls it with only one input.

Minimal case file attached

Steps to Reproduce

min_bubbler_case.json

Expected Behavior

Either:

the bubbler block should validate that both required inputs are connected and raise a clearer error, or
graph assembly / passthrough detection should not call _fn_a() with an incorrectly sized dummy input vector.

Version

No response

Browser

No response

Additional Context

[RemDelaporteMathurin]

@milanofthe While I haven't had time to look into this, it may be an upstream issue with the bubbler block in pathsim-chem? I did reproduce the issue.

[milanofthe]

Yes, I checked, usually it shoud resize the input register according to the labels automatically. Maybe this is an issue with reset. I will check later.