Unexpected output of compiling/linting a smart contract w/o a validator function

[chrissiwaffler]

Describe the bug
Compiling a smart contract without a validator function outputs an unwanted output:

Traceback (most recent call last):
  File "/Users/chrissi/Library/Caches/pypoetry/virtualenvs/opshin-_DC4-49p-py3.11/bin/opshin", line 6, in <module>
    sys.exit(main())
             ^^^^^^
  File "/Users/chrissi/Desktop/repos/cardano/OpShin Toolchain/public repo/opshin/opshin/__main__.py", line 193, in main
    annotations = list(sc.validator.__annotations__.values())
                       ^^^^^^^^^^^^
AttributeError: module '__tmp_opshin' has no attribute 'validator'

The problem is that in line 119 of opshin/__main__.py it is already expected that the smart contract has a function called validator.

Whereas this would normally be checked at a later step when the source_code gets parsed/compiled.
Then the error would be normally get caught by an assertion in the method visit_Module in opshin/compiler.py.

This impacts also the linting functionality since this is an uncaught exception and then it doesn't get printed out correctly.

To Reproduce
Steps to reproduce the behavior:

1. create a python file without an validator() function
2. run something like opshin build any broken.py
3. See unwanted output

Expected behavior
expected should be something like:

Traceback (most recent call last):
  File "/Users/chrissi/Library/Caches/pypoetry/virtualenvs/opshin-_DC4-49p-py3.11/bin/opshin", line 6, in <module>
    sys.exit(main())
             ^^^^^^
  File "/Users/chrissi/Desktop/repos/cardano/OpShin Toolchain/public repo/opshin/opshin/__main__.py", line 161, in main
    raise SyntaxError(
  File "examples/broken.py", line 1
    from opshin.prelude import *
AssertionError: Could not find function named validator
Note that opshin errors may be overly restrictive as they aim to prevent code with unintended consequences.

---

current version of the main branch with commit 9e3ad8a8c6c3d7d55262a43eb5b5b35939d33695

[chrissiwaffler]

to fix this issue we should add a test that looks something like:

    def test_no_validator_function(self):
        source_code = ""
        ast = compiler.parse(source_code)
        with self.assertRaises(CompilerError):
            compiler.compile(ast) 

this for example would be a valid test for an older commit like 12ac3122242d0c7695c9091d00241f855fb4e499 (opshin 0.13.0)

[nielstron]

Please use the newest version of OpShin (dev branch) and opshin lint lib to compile functions without validator class

[nielstron]

To make linter message valid we should definitely catch more error messages in the main function :)