diff --git a/merico/comments/main.py b/merico/comments/main.py
index 53694ea..46227fb 100644
--- a/merico/comments/main.py
+++ b/merico/comments/main.py
@@ -259,6 +259,8 @@ def main():
     code_text = selected_text.get("text", "")
 
     response = add_comments(selected_text=code_text, file_path=file_path)
+    if not response:
+        sys.exit(1)
     new_code = extract_markdown_block(response)
 
     if not new_code:
diff --git a/merico/commit/commit.py b/merico/commit/commit.py
index bbe2255..9a31c9f 100644
--- a/merico/commit/commit.py
+++ b/merico/commit/commit.py
@@ -401,6 +401,8 @@ def main():
         if branch_name:
             user_input += "\ncurrent repo branch name is:" + branch_name
         commit_message = generate_commit_message_base_diff(user_input, diff)
+        if not commit_message:
+            sys.exit(1)
 
         # TODO
         # remove Closes #IssueNumber in commit message
diff --git a/merico/docstring/main.py b/merico/docstring/main.py
index cb1811c..7171414 100644
--- a/merico/docstring/main.py
+++ b/merico/docstring/main.py
@@ -291,6 +291,8 @@ def main():
     response = add_docstring(
         selected_text=selected_text.get("text", ""), file_path=selected_text.get("abspath", "")
     )
+    if not response:
+        sys.exit(1)
 
     # Get indent level
     indent = get_indent_level(selected_text.get("text", ""))
diff --git a/merico/explain/explain.py b/merico/explain/explain.py
index 25660e2..9d9dfa7 100644
--- a/merico/explain/explain.py
+++ b/merico/explain/explain.py
@@ -83,8 +83,8 @@ def explain(selected_text, visible_text):
 
 
 def main():
-    explain(selected_text=get_selected_code(), visible_text=get_visible_code())
-    sys.exit(0)
+    result = explain(selected_text=get_selected_code(), visible_text=get_visible_code())
+    sys.exit(0 if result else 1)
 
 
 if __name__ == "__main__":
diff --git a/merico/fix/main.py b/merico/fix/main.py
index b799151..16ad7e5 100644
--- a/merico/fix/main.py
+++ b/merico/fix/main.py
@@ -141,6 +141,8 @@ def main():
 
     # rewrite
     response = fix_bugs(selected_text=selected_text, visible_text=visible_text)
+    if not response:
+        sys.exit(1)
 
     # apply new code to editor
     new_code = extract_markdown_block(response)
diff --git a/merico/refactor/names/main.py b/merico/refactor/names/main.py
index f283265..bd7dadd 100644
--- a/merico/refactor/names/main.py
+++ b/merico/refactor/names/main.py
@@ -229,6 +229,8 @@ def main():
 
     # rewrite
     response = reanme_variable(selected_text=selected_code, file_path=selected_file)
+    if not response:
+        sys.exit(1)
 
     # apply new code to editor
     new_code = extract_markdown_block(response)
diff --git a/merico/refactor/rewrite.py b/merico/refactor/rewrite.py
index b659e9b..d83f7ea 100644
--- a/merico/refactor/rewrite.py
+++ b/merico/refactor/rewrite.py
@@ -120,6 +120,8 @@ def main():
 
     # rewrite
     response = ai_rewrite(question=question, selected_text=selected_text)
+    if not response:
+        sys.exit(1)
 
     # apply new code to editor
     new_code = extract_markdown_block(response)
diff --git a/merico/unit_tests/propose_test.py b/merico/unit_tests/propose_test.py
index 1005642..8b65a9d 100644
--- a/merico/unit_tests/propose_test.py
+++ b/merico/unit_tests/propose_test.py
@@ -122,6 +122,8 @@ def propose_test(
             )
             or {}
         )
+        if not json_res:
+            raise ValueError("No valid json response")
 
     else:
         # Use the openai api parameters
diff --git a/merico/unit_tests/write_tests.py b/merico/unit_tests/write_tests.py
index 058f606..4cdff4f 100644
--- a/merico/unit_tests/write_tests.py
+++ b/merico/unit_tests/write_tests.py
@@ -138,10 +138,12 @@ def write_and_print_tests(
 
     if USE_USER_MODEL:
         # Use the wrapped api
-        _ = chat_completion_stream_out(
+        response = chat_completion_stream_out(
             messages=[{"role": "user", "content": user_msg}],
             llm_config={"model": MODEL, "temperature": 0.1},
         )
+        if not response.get("content", None):
+            raise response["error"]
 
     else:
         # Use the openai api parameters