patch 9.0.2173: Vim9: crash when compiling for statement and non-existing type

Problem:  Vim9: Vim crashes when compiling a for statement with a
          non-existing type
Solution: Error out when  lhs_type is not null

closes: #13703

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/testdir/test_vim9_script.vim

@@ -2698,6 +2698,37 @@ def Test_for_loop_fails()
   v9.CheckDefSuccess(lines)
 
   v9.CheckDefFailure(['for x in range(3)'] + lines + ['endfor'], 'E1306:')
+
+  # Test for too many for loops
+  lines =<< trim END
+    vim9script
+    def Foo()
+      for a in range(1)
+        for b in range(1)
+          for c in range(1)
+            for d in range(1)
+              for e in range(1)
+                for f in range(1)
+                  for g in range(1)
+                    for h in range(1)
+                      for i in range(1)
+                        for j in range(1)
+                          for k in range(1)
+                          endfor
+                        endfor
+                      endfor
+                    endfor
+                  endfor
+                endfor
+              endfor
+            endfor
+          endfor
+        endfor
+      endfor
+    enddef
+    defcompile
+  END
+  v9.CheckSourceFailure(lines, 'E1306: Loop nesting too deep', 11)
 enddef
 
 def Test_for_loop_script_var()
@@ -4796,6 +4827,85 @@ def Test_defer_skipped()
   v9.CheckSourceSuccess(lines)
 enddef
 
+" Test for using defer without parenthesis for the function name
+def Test_defer_func_without_paren()
+  var lines =<< trim END
+    vim9script
+    def Foo()
+      defer Bar
+    enddef
+    defcompile
+  END
+  v9.CheckScriptFailure(lines, 'E107: Missing parentheses: Bar', 1)
+enddef
+
+" Test for using defer without parenthesis for the function name
+def Test_defer_non_existing_func()
+  var lines =<< trim END
+    vim9script
+    def Foo()
+      defer Bar()
+    enddef
+    defcompile
+  END
+  v9.CheckScriptFailure(lines, 'E1001: Variable not found: Bar', 1)
+enddef
+
+" Test for using defer with an invalid function name
+def Test_defer_invalid_func()
+  var lines =<< trim END
+    vim9script
+    def Foo()
+      var Abc = 10
+      defer Abc()
+    enddef
+    defcompile
+  END
+  v9.CheckScriptFailure(lines, 'E129: Function name required', 2)
+enddef
+
+" Test for using defer with an invalid argument to a function
+def Test_defer_invalid_func_arg()
+  var lines =<< trim END
+    vim9script
+    def Bar(x: number)
+    enddef
+    def Foo()
+      defer Bar(a)
+    enddef
+    defcompile
+  END
+  v9.CheckScriptFailure(lines, 'E1001: Variable not found: a', 1)
+enddef
+
+" Test for using an non-existing type in a "for" statement.
+def Test_invalid_type_in_for()
+  var lines =<< trim END
+    vim9script
+    def Foo()
+      for b: x in range(10)
+      endfor
+    enddef
+    defcompile
+  END
+  v9.CheckSourceFailure(lines, 'E1010: Type not recognized: x in range(10)', 1)
+enddef
+
+" Test for using a line break between the variable name and the type in a for
+" statement.
+def Test_for_stmt_space_before_type()
+  var lines =<< trim END
+    vim9script
+    def Foo()
+      for a
+           :number in range(10)
+      endfor
+    enddef
+    defcompile
+  END
+  v9.CheckSourceFailure(lines, 'E1059: No white space allowed before colon: :number in range(10)', 2)
+enddef
+
 " Keep this last, it messes up highlighting.
 def Test_substitute_cmd()
   new

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2173,
 /**/
     2172,
 /**/

src/vim9cmds.c

@@ -1088,6 +1088,8 @@ compile_for(char_u *arg_start, cctx_T *cctx)
 		}
 		p = skipwhite(p + 1);
 		lhs_type = parse_type(&p, cctx->ctx_type_list, TRUE);
+		if (lhs_type == NULL)
+		    goto failed;
 	    }
 
 	    if (get_var_dest(name, &dest, CMD_for, &opt_flags,