fix: avoid errors in browser console

[pupboss]

1. onClose undefined error
2. null value has no length property
3. null value has no map function
4. Parse HTML to json object error
5. JSON.parse error exception throwed in connections.ts
6. The value in the query parameter is encoded twice

Example of no. 6:

Assume the secret is 123&abc. When used in the URL, it has already been encoded as 123%26abc. Therefore, decoding should be performed during parsing. However, the current code encodes the encoded value, resulting in %2526, causing the backend to fail to connect and report a 401 error.