[decoding] provide user feedback if string decoding might not have been successful

[mr-tz]

for example we know that we ran a function but did not get any output that is a string? can we even tell?
we know that something might have gone wrong when we get an exception, e.g. InstructionRangeExceededError

also tell user if no decoding function was found
or if function was found, but no strings could be recovered

Also: if a decoding function is called 30 times, but only 28 strings are recovered from it, something might have gone wrong (see 6ee35da59f92f71e757d4d5b964ecf00, 0x40166C for example?)