Try not to error out on invisible zero-width characters

[lucivpav]

Example input: "你好<U+200B>汽車" // renders as "你好汽車"
Current result: "Could not find data for character <U+200B>" // renders as "Could not find data for character "
Expected result: "<U+200B>" is ignored and the sheet is generated normally

https://www.ptiglobal.com/2018/04/26/the-beauty-of-unicode-zero-width-characters/