Incompatibility with different vyper versions

[PatrickAlphaC]

Environment information

• vvm Version: 0.3.1
• vyper Version: 0.4.1b1
• Python Version: 3.13.x
• OS: MacOS

What was wrong?

Loading a contract with vyper==0.4.0 when the installed vyper is 0.4.1b1, for example, like this:

boa.load("my_contract.vy")

You get this error:

Traceback (most recent call last):
  File "<python-input-1>", line 1, in <module>
    boa.load("my_contract.vy")
    ~~~~~~~~^^^^^^^^^^^^^^^^^^
  File "/path/scrap/.venv/lib/python3.13/site-packages/boa/interpret.py", line 177, in load
    return loads(f.read(), *args, name=name, **kwargs, filename=filename)
  File "/path/scrap/.venv/lib/python3.13/site-packages/boa/interpret.py", line 189, in loads
    d = loads_partial(source_code, name, filename=filename, compiler_args=compiler_args)
  File "/path/scrap/.venv/lib/python3.13/site-packages/boa/interpret.py", line 252, in loads_partial
    return _loads_partial_vvm(source_code, version, filename)
  File "/path/scrap/.venv/lib/python3.13/site-packages/boa/interpret.py", line 286, in _loads_partial_vvm
    return _disk_cache.caching_lookup(cache_key, _compile)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
  File "/path/scrap/.venv/lib/python3.13/site-packages/boa/util/disk_cache.py", line 70, in caching_lookup
    res = func()
  File "/path/scrap/.venv/lib/python3.13/site-packages/boa/interpret.py", line 277, in _compile
    return VVMDeployer.from_compiler_output(compiler_output, filename=filename)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/path/scrap/.venv/lib/python3.13/site-packages/boa/contracts/vvm/vvm_contract.py", line 41, in from_compiler_output
    abi = compiler_output["abi"]
          ~~~~~~~~~~~~~~~^^^^^^^
TypeError: string indices must be integers, not 'str'

Full Reproduction steps

mkdir scrap
cd scrap
uv venv # This is essentially `python -m venv .venv`
source .venv/bin/activate
uv add 'vyper==0.4.1b1' # this is essentially `pip install 'vyper==0.4.1b1'`
uv add titanoboa # this is essentially `pip install titanoboa`
uv init # this essentially makes a pyproject.toml
echo "#pragma version 0.4.0\nmy_value: uint256" > my_contract.vy
python

In your python shell, run:

>>>import boa
>>>boa.load("my_contract.vy")

You'll get the error.