make indents work with tabs, other whitespace chrs

[TheV360]

No description provided.

[y-ack]

[^\n\S] is not an appropriate whitespace expression for indentation, it matches:
[\f\r\t\v\u0020\u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff]

• \f FORM FEED ❌
• \r CARRIAGE RETURN ❌
• \t TAB
• \v VERTICAL TAB ❌
• \u0020 SPACE
• \u00a0 NO-BREAK SPACE
• \u1680 OGHAM SPACE MARK
• \u2000-\u200a GENERAL PUNCTUATION BLOCK spaces
• \u2028 LINE SEPARATOR ❌
• \u2029 PARAGRAPH SEPARATOR ❌
• \u202f NARROW NO-BREAK SPACE
• \u205f MEDIUM MATHEMATICAL SPACE
• \u3000 IDEOGRAPHIC SPACE
• \ufeff ZERO WIDTH NO-BREAK SPACE ❌

the problematic characters we have annotated are mostly vertical whitespace characters except for ZWNBSP which is a formatting character marked whitespace due to legacy as BYTE ORDER MARK.

[TheV360]

you should merge this..! (or if you could do it better, merge that)