Raise error if overview is requested without suitable LS support

src/serena/ls_manager.py

@@ -147,16 +147,20 @@ class LanguageServerManager:
             ls = self.restart_language_server(ls.language)
         return ls
 
+    def _get_suitable_language_server(self, relative_path: str) -> SolidLanguageServer | None:
+        """:param relative_path: relative path to a file"""
+        for candidate in self._language_servers.values():
+            if not candidate.is_ignored_path(relative_path, ignore_unsupported_files=True):
+                return candidate
+        return None
+
     def get_language_server(self, relative_path: str) -> SolidLanguageServer:
         """:param relative_path: relative path to a file"""
         ls: SolidLanguageServer | None = None
         if len(self._language_servers) > 1:
             if os.path.isdir(relative_path):
                 raise ValueError(f"Expected a file path, but got a directory: {relative_path}")
-            for candidate in self._language_servers.values():
-                if not candidate.is_ignored_path(relative_path, ignore_unsupported_files=True):
-                    ls = candidate
-                    break
+            ls = self._get_suitable_language_server(relative_path)
         if ls is None:
             ls = self._default_language_server
         return self._ensure_functional_ls(ls)
@@ -241,3 +245,6 @@ class LanguageServerManager:
         for ls in self.iter_language_servers():
             if ls.is_running():
                 ls.save_cache()
+
+    def has_suitable_ls_for_file(self, relative_file_path: str) -> bool:
+        return self._get_suitable_language_server(relative_file_path) is not None

src/serena/symbol.py

@@ -699,6 +699,9 @@ class LanguageServerSymbolRetriever:
     def get_root_path(self) -> str:
         return self._ls_manager.get_root_path()
 
+    def can_analyze_file(self, relative_file_path: str) -> bool:
+        return self._ls_manager.has_suitable_ls_for_file(relative_file_path)
+
     def get_language_server(self, relative_path: str) -> SolidLanguageServer:
         """:param relative_path: relative path to a file"""
         return self._ls_manager.get_language_server(relative_path)

src/serena/tools/symbol_tools.py

@@ -68,6 +68,10 @@ class GetSymbolsOverviewTool(Tool, ToolMarkerSymbolicRead):
             raise FileNotFoundError(f"File or directory {relative_path} does not exist in the project.")
         if os.path.isdir(file_path):
             raise ValueError(f"Expected a file path, but got a directory path: {relative_path}. ")
+        if not symbol_retriever.can_analyze_file(relative_path):
+            raise ValueError(
+                f"Cannot extract symbols from file {relative_path}. Active languages: {[l.value for l in self.agent.get_active_lsp_languages()]}"
+            )
 
         symbols = symbol_retriever.get_symbol_overview(relative_path)[relative_path]