diff --git a/src/background.js b/src/background.js
index 757d2ed..25c6b1f 100644
--- a/src/background.js
+++ b/src/background.js
@@ -285,20 +285,11 @@ const messageHandlers = {
  */
 browser.runtime.onMessage.addListener(async ({ action, args }) => {
   const handler = messageHandlers[action];
-
   if (!handler) {
-    const errorMessage = `Message action is unavailable: ${action}`;
-    kissLog("runtime onMessage", action, new Error(errorMessage));
-    return null;
+    throw new Error(`Message action is unavailable: ${action}`);
   }
 
-  try {
-    const result = await handler(args);
-    return result;
-  } catch (err) {
-    kissLog("runtime onMessage", action, err);
-    return null;
-  }
+  return handler(args);
 });
 
 /**
diff --git a/src/hooks/Alert.js b/src/hooks/Alert.js
index 817dd54..f23e04d 100644
--- a/src/hooks/Alert.js
+++ b/src/hooks/Alert.js
@@ -59,7 +59,7 @@ export function AlertProvider({ children }) {
         onClose={handleClose}
         anchorOrigin={{ vertical, horizontal }}
       >
-        <Alert onClose={handleClose} severity={severity} sx={{ width: "100%" }}>
+        <Alert onClose={handleClose} severity={severity} sx={{ maxWidth: "80%" }}>
           {message}
         </Alert>
       </Snackbar>
diff --git a/src/libs/fetch.js b/src/libs/fetch.js
index 28488d4..5ea2a96 100644
--- a/src/libs/fetch.js
+++ b/src/libs/fetch.js
@@ -41,6 +41,12 @@ export const fetchGM = async (
         });
       },
       onerror: reject,
+      onabort: () => {
+        reject(new Error("GM request onabort."));
+      },
+      ontimeout: () => {
+        reject(new Error("GM request timeout."));
+      },
     });
   });
 
diff --git a/src/views/Options/Apis.js b/src/views/Options/Apis.js
index 8d50e15..624e07a 100644
--- a/src/views/Options/Apis.js
+++ b/src/views/Options/Apis.js
@@ -77,24 +77,7 @@ function TestButton({ api }) {
       alert.error(
         <>
           <div>{i18n("test_failed")}</div>
-          {msg === err.message ? (
-            <div
-              style={{
-                maxWidth: 400,
-              }}
-            >
-              {msg}
-            </div>
-          ) : (
-            <pre
-              style={{
-                maxWidth: 400,
-                overflow: "auto",
-              }}
-            >
-              {msg}
-            </pre>
-          )}
+          {msg === err.message ? <div>{msg}</div> : <pre>{msg}</pre>}
         </>
       );
     } finally {