fix: prevent critical error message when missing self param in declar…

…ation

---------

add tests to make sure we disallow type-aliases anywhere other than module body (for now)

src/puya/awst_build/subroutine.py

@@ -154,13 +154,16 @@ def __init__(
         mypy_arg_types = type_info.arg_types
         if func_def.info is not mypy.nodes.FUNC_NO_INFO:  # why god why
             # function is a method
-            self._precondition(
-                bool(mypy_args) and mypy_args[0].variable.is_self,
-                "if function is a method, first variable should be self-like",
-                func_loc,
-            )
-            mypy_args = mypy_args[1:]
-            mypy_arg_types = mypy_arg_types[1:]
+            if not mypy_args:
+                context.error("Method declaration is missing 'self' argument", func_loc)
+            else:
+                self._precondition(
+                    mypy_args[0].variable.is_self,
+                    "if function is a method, first variable should be self-like",
+                    func_loc,
+                )
+                mypy_args = mypy_args[1:]
+                mypy_arg_types = mypy_arg_types[1:]
         elif mypy_args:
             self._precondition(
                 not mypy_args[0].variable.is_self,

tests/test_expected_output/subroutine.test

@@ -66,14 +66,22 @@ def test(a: UInt64, b: UInt64) -> UInt64:
 
 ## case: no_type_alias
 import typing
-from algopy import UInt64, subroutine
+from algopy import *
 
 @subroutine
 def test() -> UInt64:
     Foo: typing.TypeAlias = UInt64 ## E: type aliases, type vars, and type constructors are not supported inside functions
     one: Foo = UInt64(1)
     return one
 
+class MyContract(ARC4Contract):
+    Foo: typing.TypeAlias = UInt64 ## E: assignment statements are not supported in the class body
+
+    def __init__(self) -> None:
+        Bar: typing.TypeAlias = UInt64 ## E: type aliases, type vars, and type constructors are not supported inside functions
+        self.bar = Bar(1)
+
+
 ## case: no_assign_void
 from algopy import UInt64, subroutine
 
@@ -476,4 +484,4 @@ def no_op() -> None:
 @subroutine
 def test() -> None:
     if no_op():  ## E: None does not support boolean evaluation
-        pass
+        pass