If Scopus continues to answer with 429, pybliometrics will deleted all the keys until it is left with none. At the next call (after the first exception, which is correctly thrown), it will throw an IndexError. This will raise the same exception thrown the first time (Scopus429Error). This fixes #241
If Scopus continues to answer with 429, pybliometrics will deleted all the keys until it is left with none. At the next call (after the first exception, which is correctly thrown), it will throw an IndexError. This will raise the same exception thrown the first time (Scopus429Error). This fixes #241