When I try to to use memory-report-object-size I get following error on 
Emacs 28.0 pretest:


$ emacs --batch -Q --eval "(progn (require 'memory-report) (message 
\"%s\" (memory-report-object-size '(a b \"cd\"))))"
Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
   #f(compiled-function (counted value) #<bytecode 
-0x1a1202ad2c7fe610>)(#<hash-table eq 1/19 0x157c06d25887> (a b "cd"))
   apply(#f(compiled-function (counted value) #<bytecode 
-0x1a1202ad2c7fe610>) #<hash-table eq 1/19 0x157c06d25887> (a b "cd") nil)
   memory-report--object-size-1(#<hash-table eq 1/19 0x157c06d25887> (a 
b "cd"))
   memory-report--object-size(#<hash-table eq 1/19 0x157c06d25887> (a b 
"cd"))
   memory-report-object-size((a b "cd"))
   (message "%s" (memory-report-object-size '(a b "cd")))
   (progn (require 'memory-report) (message "%s" 
(memory-report-object-size '(a b "cd"))))
   command-line-1(("--eval" "(progn (require 'memory-report) (message 
\"%s\" (mem..."))
   command-line()
   normal-top-level()


While this command line does work:


$ emacs --batch -Q --eval "(progn (require 'memory-report) 
(memory-report--garbage-collect) (message \"%s\" 
(memory-report-object-size '(a b \"cd\"))))"
82


Not sure whether I'm using memory-report-object-size as intended but its 
initialization is definitely not doing anything since 
memory-report--type-size is initialized to a hash table in the same module.

Sergey