feat(resolver): add error to prevent returning value from init

src/interpreter/resolver.py

@@ -7,6 +7,7 @@ from src.ast.expr import Expr, LogicalExpr, VariableExpr, LiteralExpr, GroupingE
     AssignExpr, GetExpr, SetExpr, ThisExpr
 from src.ast.stmt import Stmt, ForStmt, WhileStmt, LetStmt, ReturnStmt, IfStmt, FunctionStmt, \
     ExpressionStmt, BlockStmt, BreakStmt, ContinueStmt, ClassStmt
+from src.consts import CONSTRUCTOR_NAME
 from src.pebble import Pebble
 from src.token import Token
 
@@ -17,6 +18,7 @@ if TYPE_CHECKING:
 class FunctionType(Enum):
     NONE = auto()
     FUNCTION = auto()
+    INITIALIZER = auto()
     METHOD = auto()
 
 
@@ -136,7 +138,10 @@ class Resolver(Expr.Visitor[None], Stmt.Visitor[None]):
         self.scopes[-1]["this"] = True
 
         for method in stmt.methods:
-            self.resolve_function(method, FunctionType.METHOD)
+            declaration: FunctionType = FunctionType.METHOD
+            if method.name.lexeme == CONSTRUCTOR_NAME:
+                declaration = FunctionType.INITIALIZER
+            self.resolve_function(method, declaration)
 
         self.end_scope()
         self.current_class = enclosing_class
@@ -160,6 +165,8 @@ class Resolver(Expr.Visitor[None], Stmt.Visitor[None]):
             Pebble.token_error(stmt.keyword, "Cannot return from top-level scope.")
 
         if stmt.value is not None:
+            if self.current_func == FunctionType.INITIALIZER:
+                Pebble.token_error(stmt.keyword, "Cannot return a value from an initializer.")
             self.resolve(stmt.value)
 
     def visit_let_stmt(self, stmt: LetStmt) -> None: