fix: initialize f=None before try in load_capa_function_results to prevent UnboundLocalError

If idaapi.get_func() raises before assignment, the except handler previously
referenced the unbound variable f, causing a secondary UnboundLocalError that
masked the original exception. Also handles the case where get_func() returns
None by falling back to idaapi.get_screen_ea() in the error log.

CHANGELOG.md

@@ -48,6 +48,9 @@
 - 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: initialize f=None before try block in load_capa_function_results to prevent UnboundLocalError in except handler @williballenthin (SURF-61)
 - fix: fix unreachable elif for NOT CompoundStatement so NOT rules render children in IDA plugin tree view @williballenthin (SURF-60)
 - fix: use next(iter(addrs)) instead of addrs.pop() to avoid mutating the feature cache in parse_features_for_tree @williballenthin (SURF-59)
 - fix: use integer division in get_printable_len for UTF-16 LE operands @williballenthin (SURF-58)

capa/ida/plugin/form.py

@@ -1011,12 +1011,14 @@ class CapaExplorerForm(idaapi.PluginForm):
         update_wait_box("extracting features")
 
         # resolve function selected in disassembly view
+        f = None
         try:
             f = idaapi.get_func(idaapi.get_screen_ea())
             if f is not None:
                 self.rulegen_current_function = self.rulegen_feature_extractor.get_function(f.start_ea)
         except Exception as e:
-            logger.exception("Failed to resolve function at address 0x%X (error: %s)", f.start_ea, e)
+            addr = f.start_ea if f else idaapi.get_screen_ea()
+            logger.exception("Failed to resolve function at address 0x%X (error: %s)", addr, e)
             return False
 
         if ida_kernwin.user_cancelled():