v2.1 having issues with "unhandled rejection" (on case of Result.Result<Text, Text> and old way of agent constructor)

[tiagoicp]

Describe the bug
On v2.0.0 no issue happens, but when I upgrade to v2.1.0 or v2.1.1, a strange exception happens when it receives the response back. It is only happening to this response, if the response is an array of ints for example, it works fine.

To Reproduce
Steps to reproduce the behavior:

0. Try to figure it out just by the screenshots. If not, then...
1. Using Plug to authenticate and a backend in motoko with a Result.Result<Text,Text>, I suspect you will face the same error.

Expected behavior
To behave as it was on v2, without any exception.

Screenshots

Desktop (please complete the following information):

• OS: Mac
• Browser: Chrome
• Version: 128

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
Original repo where the incident happened (for more context on dependencies, sequence of code, etc.): https://github.com/obsidian-tears/obsidian_tears_frontend_backend/tree/c27b4552b1f1a33eb47c1afde3262b62b3f984d5