fix(typescript): TS2322: Type 'null' is not assignable to type 'string|void'
fix(typescript): TS2322: Type 'null' is not assignable to type 'string|void'

let html: (string | null) = ... instead of let html = ... because the default
behaviour is html: (string)

KillerCodeMonkey/ng2-quill,KillerCodeMonkey/ngx-quill,KillerCodeMonkey/ng2-quill,KillerCodeMonkey/ng2-quill,KillerCodeMonkey/ngx-quill