Agents: Improve python interpreter (#31409)

* Improve Python interpreter
* Add with and assert statements
* Prevent overwriting existing tools
* Check interpreter errors are well logged in code agent
* Add lazy evaluation for and and or
* Improve variable assignment
* Fix early return statements in functions
* Add small import fix on interpreter tool

tests/agents/test_agents.py

@@ -74,6 +74,26 @@ final_answer(7.2904)
 """
 
 
+def fake_react_code_llm_error(messages, stop_sequences=None) -> str:
+    prompt = str(messages)
+    if "special_marker" not in prompt:
+        return """
+Thought: I should multiply 2 by 3.6452. special_marker
+Code:
+```py
+print = 2
+```<end_code>
+"""
+    else:  # We're at step 2
+        return """
+Thought: I can now answer the initial question
+Code:
+```py
+final_answer("got an error")
+```<end_code>
+"""
+
+
 def fake_code_llm_oneshot(messages, stop_sequences=None) -> str:
     return """
 Thought: I should multiply 2 by 3.6452. special_marker
@@ -124,6 +144,13 @@ Action:
             "tool_name": "code interpreter",
         }
 
+    def test_react_code_agent_code_errors_show_offending_lines(self):
+        agent = ReactCodeAgent(tools=[PythonInterpreterTool()], llm_engine=fake_react_code_llm_error)
+        output = agent.run("What is 2 multiplied by 3.6452?")
+        assert isinstance(output, AgentText)
+        assert output == "got an error"
+        assert "Evaluation stopped at line 'print = 2' because of" in str(agent.logs)
+
     def test_setup_agent_with_empty_toolbox(self):
         ReactJsonAgent(llm_engine=fake_react_json_llm, tools=[])