fix: sentences are probably undefined

[vellengs]

sentences probably is undefined.

translate error TypeError: Cannot read properties of undefined (reading 'filter')
    at Translator.buildResText (/xxxxxxxx/node_modules/@vitalets/google-translate-api/src/index.ts:67:8)
    at Translator.translate (/xxxxxxx/node_modules/@vitalets/google-translate-api/src/index.ts:29:23)
    at runMicrotasks (<anonymous>)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async translate (/xxxxxxxx/src/utils/Translator.ts:19:20)
    at async batchTranslate (/xxxxxxxxx/src/en.wikipedia.org/transforms/index.ts:19:20)
    at async /xxxxxxxxxx/src/en.wikipedia.org/Military_bases.translate.ts:43:9