Problem:    Vim9: LISTAPPEND instruction does not check for a locked list.
Solution:   Check whether the list is locked. (closes #9452)

Problem:    Tiny build fails.
Solution:   Adjust #ifdefs

Problem:    Error messages are spread out.
Solution:   Move the last errors from globals.h to errors.h.

Problem:    Build fails.
Solution:   Use the right error message name.

Problem:    Error messages are spread out.
Solution:   Move more errors to errors.h.

Problem:    Value of MAXCOL not available in Vim script.
Solution:   Add v:maxcol. (Naohiro Ono, closes #9451)

Problem:    Build failure.
Solution:   Add missing changes.

Problem:    Error messages are spread out.
Solution:   Move more errors to errors.h.

Problem:    When using feedkeys() abbreviations may be blocked.
Solution:   Reset tb_no_abbr_cnt when running out of characters.
            (closes #9448)

Problem:    Vim9: no easy way to check if Vim9 script is supported.
Solution:   Add has('vim9script').