When contracts return a string type starting with '0x' like '0x9e' , brwonie may have an error

[kejaly]

Environment information

• brownie Version: v1.19.3

What was wrong?

When Brownie returns a string starting with "0x", it will go to unhex it , which leads to an error if you want to directly return a string starting with "0x", such as "0x9e".

The test code is as follows:
the left is test0x.sol , and the right is test.py

and I found out that the reason is the _format_single function :

when the type is string ,it will call to_string(value) , and in the to_string function , it will try to unhex the value ,if it is start with a '0x':

How can it be fixed

in my opinion, i think since it is already a string type, you can directly return str(value) instead of calling to_string(value)

[BobTheBuidler]

based on the signature of _format_single, we don't have any reason to expect value is already a string object

Another solution seems necessary here, any ideas?