Improve LS-related error handling, reporting and propagation

src/serena/agent.py

@@ -86,7 +86,7 @@ class SerenaAgent:
 
         # project-specific instances, which will be initialized upon project activation
         self._active_project: Project | None = None
-        self.language_server_manager: LanguageServerManager | None = None
+        self._language_server_manager: LanguageServerManager | None = None
 
         # adjust log level
         serena_log_level = self.serena_config.log_level
@@ -192,6 +192,18 @@ class SerenaAgent:
                 process.start()
                 process.join(timeout=1)
 
+    def get_language_server_manager(self) -> LanguageServerManager | None:
+        return self._language_server_manager
+
+    def get_language_server_manager_or_raise(self) -> LanguageServerManager:
+        if self._language_server_manager is None:
+            raise Exception(
+                "The language server manager is not initialized, indicating a problem during project activation. "
+                "Inform the user, telling them to inspect Serena's logs in order to determine the issue. "
+                "IMPORTANT: Wait for further instructions before you continue!"
+            )
+        return self._language_server_manager
+
     def get_context(self) -> SerenaAgentContext:
         return self._context
 
@@ -518,13 +530,13 @@ class SerenaAgent:
             ls_timeout = tool_timeout - 5  # the LS timeout is for a single call, it should be smaller than the tool timeout
 
         # stop the language server if it is running
-        if self.language_server_manager is not None:
-            self.language_server_manager.stop_all()
-            self.language_server_manager = None
+        if self._language_server_manager is not None:
+            self._language_server_manager.stop_all()
+            self._language_server_manager = None
 
-        # instantiate and start the necessarys language servers
-        assert self._active_project is not None
-        self.language_server_manager = self._active_project.create_language_server_manager(
+        # instantiate and start the necessary language servers
+        assert self._active_project is not None, "Active project required"
+        self._language_server_manager = self._active_project.create_language_server_manager(
             log_level=self.serena_config.log_level,
             ls_timeout=ls_timeout,
             trace_lsp_communication=self.serena_config.trace_lsp_communication,
@@ -544,9 +556,9 @@ class SerenaAgent:
         if not hasattr(self, "_is_initialized"):
             return
         log.info("SerenaAgent is shutting down ...")
-        if self.language_server_manager is not None:
-            self.language_server_manager.stop_all(save_cache=True)
-            self.language_server_manager = None
+        if self._language_server_manager is not None:
+            self._language_server_manager.stop_all(save_cache=True)
+            self._language_server_manager = None
         if self._gui_log_viewer:
             log.info("Stopping the GUI log window ...")
             self._gui_log_viewer.stop()

src/serena/tools/tools_base.py

@@ -47,8 +47,7 @@ class Component(ABC):
     def create_language_server_symbol_retriever(self) -> LanguageServerSymbolRetriever:
         if not self.agent.is_using_language_server():
             raise Exception("Cannot create LanguageServerSymbolRetriever; agent is not in language server mode.")
-        language_server_manager = self.agent.language_server_manager
-        assert language_server_manager is not None
+        language_server_manager = self.agent.get_language_server_manager_or_raise()
         return LanguageServerSymbolRetriever(language_server_manager, agent=self.agent)
 
     @property
@@ -239,7 +238,7 @@ class Tool(Component):
             try:
                 # check whether the tool requires an active project and language server
                 if not isinstance(self, ToolMarkerDoesNotRequireActiveProject):
-                    if self.agent._active_project is None:
+                    if self.agent.get_active_project() is None:
                         return (
                             "Error: No active project. Ask the user to provide the project path or to select a project from this list of known projects: "
                             + f"{self.agent.serena_config.project_names}"
@@ -251,11 +250,11 @@ class Tool(Component):
                 except SolidLSPException as e:
                     if e.is_language_server_terminated():
                         affected_language = e.get_affected_language()
-                        if affected_language is not None and self.agent.language_server_manager is not None:
+                        if affected_language is not None:
                             log.error(
                                 f"Language server terminated while executing tool ({e}). Restarting the language server and retrying ..."
                             )
-                            self.agent.language_server_manager.restart_language_server(affected_language)
+                            self.agent.get_language_server_manager_or_raise().restart_language_server(affected_language)
                             result = apply_fn(**kwargs)
                         else:
                             log.error(
@@ -271,7 +270,7 @@ class Tool(Component):
             except Exception as e:
                 if not catch_exceptions:
                     raise
-                msg = f"Error executing tool: {e}"
+                msg = f"Error executing tool: {e.__class__.__name__} - {e}"
                 log.error(f"Error executing tool: {e}", exc_info=e)
                 result = msg
 
@@ -279,8 +278,9 @@ class Tool(Component):
                 log.info(f"Result: {result}")
 
             try:
-                if self.agent.language_server_manager is not None:
-                    self.agent.language_server_manager.save_all_caches()
+                ls_manager = self.agent.get_language_server_manager()
+                if ls_manager is not None:
+                    ls_manager.save_all_caches()
             except Exception as e:
                 log.error(f"Error saving language server cache: {e}")