BR: LocalisedStrings asserts if translation is missing

To reproduce:

juce::LocalisedStrings ls ( "\"a\" = ", false );

Issue:

    /** Moves this pointer along to the next character in the string. */
    CharPointer_UTF8& operator++() noexcept
    {
        jassert (*data != 0); // trying to advance past the end of the string?
        auto n = (signed char) *data++;

        if (n < 0)
        {
            uint8 bit = 0x40;

            while ((static_cast<uint8> (n) & bit) != 0 && bit > 0x8)
            {
                ++data;
                bit = static_cast<uint8> (bit >> 1);
            }
        }

        return *this;
    }

Asserts and then reads off the end of the end of the string.