Outer '?' is considered too complex with nested groups

[illya-laifu]

Hello,

given regex: seq1-(seq2-([a-zA-Z0-9]+))?, the cli program fails with:

❯ ./zig-out/bin/regex "seq1-(seq2-([a-zA-Z0-9]+))?" "seq1-seq2-kappa123"
error: invalid pattern: PatternTooComplex

However, moving it into inner group still works correctly:

❯ ./zig-out/bin/regex "seq1-(seq2-([a-zA-Z0-9]+)?)" "seq1-seq2-kappa123"
seq1-seq2-kappa123

Matching with only one group also works just fine:

❯ ./zig-out/bin/regex "seq2-([a-zA-Z0-9]+)?" "seq2-kappa123"
seq2-kappa123