fix: resolve pre-existing mypy errors on files touched by this PR

The prek mypy hook runs on changed files and bypasses the pyproject.toml
tests/ exclude, surfacing pre-existing errors in both context.py and
test_context.py that block CI for this PR. Fixes applied:

- Import Language from language_enum instead of base (base re-exports are
  not explicit; strict mypy flags attr-defined)
- Annotate _extract_class_declaration, _import_to_statement,
  get_java_imported_type_skeletons, and resolved_imports
- Guard None start/end_line in _extract_function_source_by_lines and
  find_helper_functions; guard None file_path in the import skeleton loop
- Drop unreachable `if not node: continue` in _extract_public_method_signatures
  (JavaMethodNode.node is non-nullable)
- Add -> None to every test method and fix an `int | None` comparison in
  test_context.py

All 880 Java tests pass after the change.

Author: mohamedashrraf222

codeflash/languages/java/context.py

@@ -11,18 +11,20 @@
 from typing import TYPE_CHECKING
 
 from codeflash.code_utils.code_utils import encoded_tokens_len
-from codeflash.languages.base import CodeContext, HelperFunction, Language
+from codeflash.languages.base import CodeContext, HelperFunction
 from codeflash.languages.java.discovery import discover_functions_from_source
 from codeflash.languages.java.import_resolver import JavaImportResolver, find_helper_files
 from codeflash.languages.java.parser import get_java_analyzer
+from codeflash.languages.language_enum import Language
 
 if TYPE_CHECKING:
     from pathlib import Path
 
     from tree_sitter import Node
 
     from codeflash.discovery.functions_to_optimize import FunctionToOptimize
-    from codeflash.languages.java.parser import JavaAnalyzer, JavaMethodNode
+    from codeflash.languages.java.import_resolver import ResolvedImport
+    from codeflash.languages.java.parser import JavaAnalyzer, JavaImportInfo, JavaMethodNode
 
 logger = logging.getLogger(__name__)
 
@@ -360,7 +362,7 @@ def _extract_type_declaration(type_node: Node, source_bytes: bytes, type_kind: s
 
 
 # Keep old function name for backwards compatibility
-def _extract_class_declaration(node, source_bytes):
+def _extract_class_declaration(node: Node, source_bytes: bytes) -> str:
     return _extract_type_declaration(node, source_bytes, "class")
 
 
@@ -629,6 +631,8 @@ def _extract_function_source_by_lines(source: str, function: FunctionToOptimize)
 
     start_line = function.doc_start_line or function.starting_line
     end_line = function.ending_line
+    if start_line is None or end_line is None:
+        return ""
 
     # Convert from 1-indexed to 0-indexed
     start_idx = start_line - 1
@@ -672,6 +676,8 @@ def find_helper_functions(
                 func_id = f"{file_path}:{func.qualified_name}"
                 if func_id not in visited_functions:
                     visited_functions.add(func_id)
+                    if func.starting_line is None or func.ending_line is None:
+                        continue
 
                     # Extract the function source using tree-sitter for resilient lookup
                     func_source = extract_function_source(source, func, analyzer=analyzer)
@@ -795,7 +801,7 @@ def extract_read_only_context(source: str, function: FunctionToOptimize, analyze
     return "\n".join(context_parts)
 
 
-def _import_to_statement(import_info) -> str:
+def _import_to_statement(import_info: JavaImportInfo) -> str:
     """Convert a JavaImportInfo to an import statement string.
 
     Args:
@@ -898,7 +904,11 @@ def _extract_type_names_from_code(code: str, analyzer: JavaAnalyzer) -> set[str]
 
 
 def get_java_imported_type_skeletons(
-    imports: list, project_root: Path, module_root: Path | None, analyzer: JavaAnalyzer, target_code: str = ""
+    imports: list[JavaImportInfo],
+    project_root: Path,
+    module_root: Path | None,
+    analyzer: JavaAnalyzer,
+    target_code: str = "",
 ) -> str:
     """Extract type skeletons for project-internal imported types.
 
@@ -933,7 +943,7 @@ def get_java_imported_type_skeletons(
     priority_types = _extract_type_names_from_code(target_code, analyzer)
 
     # Pre-resolve all imports, expanding wildcards into individual types
-    resolved_imports: list = []
+    resolved_imports: list[ResolvedImport] = []
     for imp in imports:
         if imp.is_wildcard:
             # First try unfiltered expansion with a cap. If the package is small enough, take all types.
@@ -978,7 +988,7 @@ def get_java_imported_type_skeletons(
 
     for resolved in resolved_imports:
         class_name = resolved.class_name
-        if not class_name:
+        if not class_name or resolved.file_path is None:
             continue
 
         dedup_key = (str(resolved.file_path), class_name)
@@ -1100,8 +1110,6 @@ def _extract_public_method_signatures(source: str, class_name: str, analyzer: Ja
             continue
 
         node = method.node
-        if not node:
-            continue
 
         # Check if the method is public
         is_public = False