This is not the problem. The Op's regex guarantees that something of $1,$2,$3,$4 will be undefined even if the true/false sense of a "match" succeeds.

For example, a line can only start with one thing.
e.g, $2 and $3 cannot both be "defined" at the same time...
A line can start with one of these 2 things or something else.
   "Query = "
   ">something"
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The Ops "Length = .*" term will never match unless the line didn't start with Query or > because the .* in those terms will "greedily" gobble up all the characters past those terms in the line. In that case $2 and $3 will be undefined. This is actually ok if that is what was intended.