vim-patch:9.0.0360: crash when invalid line number on :for is ignored

Problem:    Crash when invalid line number on :for is ignored.
Solution:   Do not check breakpoint for non-existing line.
35d21c6830

Test does not fail without the fix in Nvim as Nvim uses 0 when line
number overflows. If it is changed to MAXLNUM then the test does fail
without the fix, but using 0 seems better as E481 is still given.

src/nvim/ex_docmd.c

@@ -642,7 +642,7 @@ int do_cmdline(char *cmdline, LineGetter fgetline, void *cookie, int flags)
 
           // Check for the next breakpoint at or after the ":while"
           // or ":for".
-          if (breakpoint != NULL) {
+          if (breakpoint != NULL && lines_ga.ga_len > current_line) {
             *breakpoint = dbg_find_breakpoint(getline_equal(fgetline, cookie, getsourceline), fname,
                                               ((wcmd_T *)lines_ga.ga_data)[current_line].lnum - 1);
             *dbg_tick = debug_tick;

src/nvim/testdir/test_eval_stuff.vim

@@ -1,5 +1,8 @@
 " Tests for various eval things.
 
+source view_util.vim
+source shared.vim
+
 function s:foo() abort
   try
     return [] == 0
@@ -87,6 +90,18 @@ func Test_for_over_null_string()
   let &enc = save_enc
 endfunc
 
+func Test_for_invalid_line_count()
+  let lines =<< trim END
+      111111111111111111111111 for line in ['one']
+      endfor
+  END
+  call writefile(lines, 'XinvalidFor')
+  " only test that this doesn't crash
+  call RunVim([], [], '-u NONE -e -s -S XinvalidFor -c qa')
+
+  call delete('XinvalidFor')
+endfunc
+
 func Test_readfile_binary()
   new
   call setline(1, ['one', 'two', 'three'])