/([^])\1+/g
1st Capturing group ([^])
[^] match any character (Note: Avoid this construct, use . or [\s\S] instead.)
\1 matches the same text as most recently matched by the 1st capturing group
Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
g modifier: global. All matches (don't return on first match)

To explore this further, go to https://regex101.com/r/zX7aN0/1

That solution appears to work. Only the second argument should ever be undefined (indicating that there are no minor words). What error do you get?

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