使用Python调用MiniZinc+OR-Tools求解器时JSON解析报错

我通过MiniZinc Python库在Python中调用MiniZinc，代码如下：

model = Model()
_solver = Solver.lookup(solver)
inst = Instance(_solver, model)
if len(model_file) > 0:
    for f in model_file:
        inst.add_file(f)
        inst.add_string("\n")
if len(model_text) > 0:
    text = ""
    for t in model_text:
        text += t + "\n"
    inst.add_string(text)
result = inst.solve(timeout=timedelta(seconds=timeout))

使用Gecode求解器时运行正常，但切换为OR-Tools求解器后，执行inst.solve(...)时抛出错误：

File "/Users/gaby/Github/simulations/.venv/lib/python3.12/site-packages/minizinc/instance.py", line 235, in solve_async
    async for result in self.solutions(
  File "/Users/gaby/Github/simulations/.venv/lib/python3.12/site-packages/minizinc/instance.py", line 373, in solutions
    async for obj in decode_async_json_stream(
  File "/Users/gaby/Github/simulations/.venv/lib/python3.12/site-packages/minizinc/json.py", line 103, in decode_async_json_stream
    obj = loads(buffer, cls=cls, **kw)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.12/3.12.4/Frameworks/Python.framework/Versions/3.12/lib/python3.12/json/__init__.py", line 359, in loads
    return cls(**kw).decode(s)
           ^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.12/3.12.4/Frameworks/Python.framework/Versions/3.12/lib/python3.12/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.12/3.12.4/Frameworks/Python.framework/Versions/3.12/lib/python3.12/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

已尝试以下操作：

• 使用MiniZinc IDE搭配OR-Tools求解器运行同一模型，可正常运行，说明配置无问题。
• 在Python中使用Gecode求解器调用instance.solve()，可正常求解。
• 确认Python能找到OR-Tools求解器（Solver.lookup(solver)可成功查找）。

期望能在Python中使用OR-Tools作为求解器运行MiniZinc（尤其需要在pytest中使用），求解决方案。

内容的提问来源于stack exchange，提问作者GabyLP