fix: use ModuleNotFoundError, add has_ts_parser flag, add fallback test

- except ImportError -> except ModuleNotFoundError (won't swallow
  real init errors from an installed-but-broken package)
- Added self.has_ts_parser attribute for downstream consumers
- Added test_fallback_when_ts_parser_missing: monkeypatches
  _HAS_TS_PARSER=False, verifies init succeeds, flag is False,
  and JS fallback still parses TS imports correctly

Author: DevanshuNEU

backend/services/dependency_analyzer.py

@@ -12,7 +12,7 @@
 try:
     import tree_sitter_typescript as tstypescript
     _HAS_TS_PARSER = True
-except ImportError:
+except ModuleNotFoundError:
     _HAS_TS_PARSER = False
 from tree_sitter import Language, Parser
 
@@ -33,13 +33,14 @@ def __init__(self):
             ts_lang = js_lang
             tsx_lang = js_lang
 
+        self.has_ts_parser = _HAS_TS_PARSER
         self.parsers = {
             'python': Parser(Language(tspython.language())),
             'javascript': Parser(js_lang),
             'typescript': Parser(ts_lang),
             'tsx': Parser(tsx_lang),
         }
-        logger.info("DependencyAnalyzer initialized", ts_parser=_HAS_TS_PARSER)
+        logger.info("DependencyAnalyzer initialized", ts_parser=self.has_ts_parser)
 
     def _detect_language(self, file_path: str) -> str:
         """Detect language from file extension"""

backend/tests/test_dependency_analyzer.py

@@ -103,6 +103,23 @@ def test_ts_parser_is_not_js(self, analyzer):
         # They should be different Language objects
         assert ts_parser is not js_parser
 
+    def test_has_ts_parser_flag(self, analyzer):
+        assert analyzer.has_ts_parser is True
+
+    def test_fallback_when_ts_parser_missing(self, monkeypatch, tmp_path):
+        """App must not crash if tree-sitter-typescript is missing"""
+        import services.dependency_analyzer as mod
+        monkeypatch.setattr(mod, '_HAS_TS_PARSER', False)
+        from services.dependency_analyzer import DependencyAnalyzer
+        fallback = DependencyAnalyzer()
+        # Should initialize without error
+        assert fallback.has_ts_parser is False
+        # Should still parse TS files (using JS fallback)
+        ts_file = tmp_path / "test.ts"
+        ts_file.write_text('import { foo } from "./bar"')
+        result = fallback.analyze_file_dependencies(str(ts_file))
+        assert './bar' in result['imports']
+
 
 class TestLanguageDetection:
     """Verify file extension to language mapping"""