fix: guard parse_node against missing "type" key to avoid TypeError crash

When "type" is absent from node_data, node_data.get(None) returns None
and "description" in None raises TypeError. Guard with early returns.

Closes SURF-73

CHANGELOG.md

@@ -48,8 +48,7 @@
 - fix: remove unreachable backports.functools_lru_cache fallback and dead dependency @williballenthin
 - fix: Scopes.from_dict uses cls instead of self so subclasses return the correct type @williballenthin
 - fix: correct wrong dict key in VMRay _compute_monitor_threads assertion (used thread_id instead of process_id) @williballenthin
-fix: replace assert with isinstance guard in get_callee for invalid MethodSpec tokens @williballenthin
-- fix: replace assert with isinstance guard in get_callee for invalid MethodSpec tokens @williballenthin
+- fix: guard parse_node against missing "type" key to avoid TypeError crash @williballenthin (SURF-73)
 - fix: allocate feat_dict per feature in parse_json to avoid shared-reference aliasing @williballenthin (SURF-72)
 - fix: add missing capa.features.extractors.elf import to ghidra/helpers.py and ida/helpers.py @williballenthin (SURF-71)
 - fix: remove dead view_tab_rulegen assignment from CapaExplorerForm that was never read @williballenthin (SURF-70)

capa/ghidra/plugin/capa_explorer.py

@@ -313,7 +313,14 @@ def get_locations(match_dict):
 def parse_node(node_data):
     """pull match descriptions and sub features by parsing node dicts"""
 
-    node = node_data.get(node_data.get("type"))
+    node_type = node_data.get("type")
+    if node_type is None:
+        logger.debug("parse_node: node_data missing 'type' key: %s", node_data)
+        return
+    node = node_data.get(node_type)
+    if not isinstance(node, dict):
+        logger.debug("parse_node: node_data[%s] is not a dict: %s", node_type, type(node))
+        return
 
     if "description" in node:
         yield "description", node.get("description")