Right. The added complexity actually comes from introducing the say function, which takes a list.

say (caller(0))[0];
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is expanding to:

say $package, $filename, $line, $subroutine, $hasargs,$wantarray, $eva
+ltext, $is_require, $hints, $bitmask, $hinthash,[0];
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This gives you the syntax error:

say [0];
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