Unhandled exception during autocomplete fix

click_repl/_completer.py

@@ -274,7 +274,10 @@ def get_completions(self, document, complete_event=None):
 
         if self.parsed_args != args:
             self.parsed_args = args
-            self.parsed_ctx = _resolve_context(args, self.ctx)
+            try:
+                self.parsed_ctx = _resolve_context(args, self.ctx)
+            except Exception:
+                return []  # autocompletion for nonexistent cmd can throw here
             self.ctx_command = self.parsed_ctx.command
 
         if getattr(self.ctx_command, "hidden", False):

tests/test_completion/test_common_tests/test_cmd_completion.py

@@ -0,0 +1,35 @@
+import click
+from unittest import TestCase
+from prompt_toolkit.document import Document
+from click_repl import ClickCompleter
+
+
+@click.group()
+def cli():
+    pass
+
+
+@cli.group()
+def cmd():
+    pass
+
+
+@cmd.command()
+def subcmd():
+    pass
+
+
+class Test_Command_Autocompletion(TestCase):
+    def setUp(self):
+        self.c = ClickCompleter(cli, click.Context(cli))
+
+    def test_valid_subcmd(self):
+        res = list(self.c.get_completions(Document("cmd s")))
+        self.assertListEqual([i.text for i in res], ["subcmd"])
+
+    def test_not_valid_subcmd(self):
+        try:
+            res = list(self.c.get_completions(Document("not cmd")))
+        except Exception as e:
+            self.fail(f"Autocompletion raised exception: {e}")
+        self.assertListEqual(res, [])