Error message improvment

[vivianjeng]

https://github.com/vivianjeng/explorer/issues/2

[kittybest]

• Now if I cancel the signature, it looks like this ⬇️

should it just look like this, or do we have to do some styling to it?

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Now it will display "Deployer does not match", does this satisfy the original issue?

[vivianjeng]

@ChialiT