Steps to replicate the issue:
Run pwb wikibase_tests -v TestWikibaseParser of https://gerrit.wikimedia.org/r/c/pywikibot/core/+/297637
What happens?:
The test fails due to this assert statement in api.Request.submit() introduced in rPWBCd179b13:
assert isinstance(result[key], str), \
'Unexpected {}: {!r}'.format(key, result[key])but the result[key] is valid:
result[key] [{'raw': 'Not a quantity', 'error': 'ValueParsers\\ParseException', 'error-info': 'Malformed quantity', 'expected-format': 'quantity', 'messages': [{'name': 'wikibase-parse-error-quantity', 'parameters': [], 'html': {'*': 'Der Mengenwert ist ungültig.'}}]}] <class 'list'>
E