fix: guard find_code_blocks against None LM response

rlm/utils/parsing.py

@@ -7,11 +7,14 @@
 from rlm.core.types import REPLResult, RLMIteration
 
 
-def find_code_blocks(text: str) -> list[str]:
+def find_code_blocks(text: str | None) -> list[str]:
     """
     Find REPL code blocks in text wrapped in triple backticks and return List of content(s).
     Returns None if no code blocks are found.
     """
+    if not text:
+        return []
+
     pattern = r"```repl\s*\n(.*?)\n```"
     results = []
 

tests/test_parsing.py

@@ -45,6 +45,16 @@ def test_no_code_blocks(self):
         blocks = find_code_blocks(text)
         assert blocks == []
 
+    def test_none_text_returns_empty_list(self):
+        """LM clients can return None content (e.g. under tool-use pressure);
+        this must not raise a TypeError."""
+        blocks = find_code_blocks(None)
+        assert blocks == []
+
+    def test_empty_string_returns_empty_list(self):
+        blocks = find_code_blocks("")
+        assert blocks == []
+
     def test_non_repl_code_blocks_ignored(self):
         text = """Python block:
 ```python