fix: resolves #2563

src/actions/public/watchContractEvent.test.ts

@@ -1567,4 +1567,34 @@ describe('subscribe', () => {
       unwatch()
     })
   })
+
+  test(
+    'https://github.com/wevm/viem/issues/2563',
+    async () => {
+      let error: Error | undefined
+      const unwatch = watchContractEvent(webSocketClient, {
+        ...usdcContractConfig,
+        onError: (error_) => {
+          error = error_
+        },
+        onLogs: () => {},
+      })
+
+      await wait(100)
+      const { socket } = await webSocketClient.transport.getRpcClient()
+      socket.close()
+      await wait(100)
+
+      expect(error).toMatchInlineSnapshot(`
+        [SocketClosedError: The socket has been closed.
+
+        URL: http://localhost
+
+        Version: [email protected]]
+      `)
+
+      unwatch()
+    },
+    { timeout: 10_000 },
+  )
 })

src/clients/transports/webSocket.test.ts

@@ -185,6 +185,39 @@ test('subscribe', async () => {
   expect(blocks.length).toBe(1)
 })
 
+test('throws on socket closure', async () => {
+  const transport = webSocket(anvilMainnet.rpcUrl.ws, {
+    key: 'jsonRpc',
+    name: 'JSON RPC',
+  })({})
+  if (!transport.value) return
+
+  let error: Error | undefined
+  const { subscriptionId } = await transport.value.subscribe({
+    params: ['newHeads'],
+    onData: () => {},
+    onError: (error_) => {
+      error = error_
+    },
+  })
+
+  // Make sure we are subscribed.
+  expect(subscriptionId).toBeDefined()
+
+  await wait(100)
+  const { socket } = await transport.value.getRpcClient()
+  socket.close()
+  await wait(100)
+
+  expect(error).toMatchInlineSnapshot(`
+    [SocketClosedError: The socket has been closed.
+
+    URL: http://localhost
+
+    Version: [email protected]]
+  `)
+})
+
 test('throws on bogus subscription', async () => {
   const transport = webSocket(anvilMainnet.rpcUrl.ws, {
     key: 'jsonRpc',

src/clients/transports/webSocket.ts

@@ -144,6 +144,11 @@ export function webSocket(
                   method: 'eth_subscribe',
                   params,
                 },
+                onError(error) {
+                  reject(error)
+                  onError?.(error)
+                  return
+                },
                 onResponse(response) {
                   if (response.error) {
                     reject(response.error)