Return a proper error message when we have type mismatching

[kostyantyn]

It took a lot of time to understand this broken test

--- FAIL: TestClickEvent (0.00s)
    Location:   click_test.go:70
    Error:      Not equal: 2 (expected)
                    != 2 (actual)

and the reason was that those values had different types: int32 and int.

Would be really good to return a proper error message.

[matryer]

Maybe if both values are the same, we include the type? Or include the type always?

[jonahkagan]

👍 this behavior changed recently and caused very confusing test failures

[mpictor]

Making it more strict about types is good, but doing so without printing types is bad!

👍 on this creating confusing test failures and needing to be fixed