The bug

When parsing ERC-681 encoded URIs or QR Codes for ERC-20 token transactions, the uint256 parameter is parsed wrong.

MetaMask seems to assume the uint256 value is on main token unit, instead of atomic unit.

Example:
ethereum:0xdAC17F958D2ee523a2206206994597C13D831ec7/transfer?address=0x8e23ee67d1332ad560396262c48ffbb01f93d052&uint256=1500000

should be parsed to 1.5 USDT, but instead is parsed as 1.5 million USDT

In order to parse 1.5 USDT the URI needs to be constructed like:

ethereum:0xdAC17F958D2ee523a2206206994597C13D831ec7/transfer?address=0x8e23ee67d1332ad560396262c48ffbb01f93d052&uint256=1.5

Which not only doesn't match what's on the spec (https://github.com/ethereum/EIPs/blob/master/EIPS/eip-681.md)

Requesting payments in ERC #20 tokens involves a request to call the transfer function of the token contract with an address and a uint256 typed parameter, containing the beneficiary address and the amount in atomic units, respectively.

but also makes no sense, since it's supposed to be a unsigned integer, not a decimal value.

To Reproduce

1. Generate a ERC-20 token QR Code or payment URI (https://brunobar79.github.io/eip681-link-generator/)
2. Parse it with MetaMask

Expected behavior
Token value parsed in atomic units

Smartphone (please complete the following information):

• Device: Galaxy S9
• OS: Android 10
• Version: 28