In some very rare cases it was possible to get an interpreter crash because of this bug. Fixes #1087

jedi/evaluate/compiled/mixed.py

@@ -166,11 +166,10 @@ def _find_syntax_node_name(evaluator, access_handle):
         return None  # It's too hard to find lambdas.
 
     # Doesn't always work (e.g. os.stat_result)
-    try:
+    names = module_node.get_used_names().get(name_str, [])
-        names = module_node.get_used_names()[name_str]
-    except KeyError:
-        return None
     names = [n for n in names if n.is_definition()]
+    if not names:
+        return None
 
     try:
         code = python_object.__code__

test/test_api/test_interpreter.py

@@ -341,3 +341,18 @@ def test_dir_magic_method():
 
     foo = [c for c in completions if c.name == 'foo'][0]
     assert foo._goto_definitions() == []
+
+
+def test_name_not_findable():
+    class X():
+        if 0:
+            NOT_FINDABLE
+
+        def hidden(self):
+            return
+
+        hidden.__name__ = 'NOT_FINDABLE'
+
+    setattr(X, 'NOT_FINDABLE', X.hidden)
+
+    assert jedi.Interpreter("X.NOT_FINDA", [locals()]).completions()