Update Utils.rs

[MohammadAbuzar945]

Here's a rephrased version of your message:

I’ve updated the error message that appears due to a consistent issue:

Err(
    reqwest::Error {
        kind: Decode,
        source: Error("missing field `data`", line: 1, column: 219),
    },
)

This error always occurs when the wrong plan_id is provided. For example, it happens if you're using a live key with a plan from the test environment.

I’ve added instructions to help users easily identify this issue, and I’m opening a pull request with the update.

Let me know if this works!