ethers::utils::parse_units panics on unknown units

[MartinquaXD]

Version
0.6.0

Platform
Linux x13 5.15.6-2-MANJARO #1 SMP PREEMPT Sat Dec 4 11:11:58 UTC 2021 x86_64 GNU/Linux

Description
Calling parse_units with an unknown unit panics.

I tried this code:

ethers::utils::parse_units("1234", "ethe");

Which resulted in:

thread 'main' panicked at 'unrecognized units'

Because the function signature suggests problems are being reported as an error return value, I expected an error instead of a panic.
Please consider returning an error or documenting the panic behavior.

As a side note: If it's possible, please consider making the Error return type implement Send + Sync to improve the ergonomics with error handling crates like anyhow.