patch 8.2.2512: Vim9: compiling error test sometimes fails

Problem:    Vim9: compiling error test sometimes fails.
Solution:   use WaitForAssert() instead of sleeping for a bit. (Dominique
            Pellé, closes #7837)

src/testdir/term_util.vim

@@ -179,5 +179,9 @@ func Run_shell_in_terminal(options)
   return buf
 endfunc
 
+" Return concatenated lines in terminal.
+func Term_getlines(buf, lines)
+  return join(map(a:lines, 'term_getline(a:buf, v:val)'), '')
+endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab

src/testdir/test_vim9_func.vim

@@ -31,18 +31,8 @@ def TestCompilingError()
   call writefile(lines, 'XTest_compile_error')
   var buf = RunVimInTerminal('-S XTest_compile_error',
               {rows: 10, wait_for_ruler: 0})
-  var text = ''
+  call WaitForAssert(() => assert_match('Error detected while compiling command line.*Fails.*Variable not found: nothing',
-  for loop in range(100)
+                     Term_getlines(buf, range(1, 9))))
-    text = ''
-    for i in range(1, 9)
-      text ..= term_getline(buf, i)
-    endfor
-    if text =~ 'Variable not found: nothing'
-      break
-    endif
-    sleep 20m
-  endfor
-  assert_match('Error detected while compiling command line.*Fails.*Variable not found: nothing', text)
 
   # clean up
   call StopVimInTerminal(buf)

src/testdir/test_vim9_script.vim

@@ -755,7 +755,7 @@ def Test_throw_vimscript()
 enddef
 
 def Test_error_in_nested_function()
-  # an error in a nested :function aborts executin in the calling :def function
+  # an error in a nested :function aborts executing in the calling :def function
   var lines =<< trim END
       vim9script
       def Func()

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2512,
 /**/
     2511,
 /**/