The conditional open tag requires the -> delimiter. Written as
<has series#>, the engine does not recognize a conditional, so the
later <-has> closes the enclosing <if series-> instead and the template
reports "Missing <-if series> closing conditional." while leaking the
literal text "<has series#>" into the name.
Also add a nested-conditional example, since the reference table only
shows each conditional in isolation, plus regression tests for
<has series#-> nested inside <if series-> when a book is in a series
but has no series number.
Co-authored-by: rmcrackan <rmcrackan@gmail.com>