patch 8.2.1431: Vim9: no error for white space before comma in dict

Problem:    Vim9: no error for white space before comma in dict.
Solution:   Check for extra white space. (closes #6674)
diff --git a/src/dict.c b/src/dict.c
index b6c9016..a5569e6 100644
--- a/src/dict.c
+++ b/src/dict.c
@@ -922,7 +922,12 @@
 	if (!had_comma)
 	{
 	    if (evaluate)
-		semsg(_(e_missing_dict_comma), *arg);
+	    {
+		if (**arg == ',')
+		    semsg(_(e_no_white_before), ",");
+		else
+		    semsg(_(e_missing_dict_comma), *arg);
+	    }
 	    goto failret;
 	}
     }
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index e963d94..09792ef 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -1506,6 +1506,7 @@
   call CheckDefFailure(["let x = #{a:8}"], 'E1069:')
   call CheckDefFailure(["let x = #{a : 8}"], 'E1068:')
   call CheckDefFailure(["let x = #{a :8}"], 'E1068:')
+  call CheckDefFailure(["let x = #{a: 8 , b: 9}"], 'E1068:')
 
   call CheckDefFailure(["let x = #{8: 8}"], 'E1014:')
   call CheckDefFailure(["let x = #{xxx}"], 'E720:')
@@ -1577,6 +1578,12 @@
       let d = #{one:1}
   END
   CheckScriptFailure(lines, 'E1069:')
+
+  lines =<< trim END
+      vim9script
+      let d = #{one: 1 , two: 2}
+  END
+  CheckScriptFailure(lines, 'E1068:')
 enddef
 
 let g:oneString = 'one'
diff --git a/src/version.c b/src/version.c
index 7bafa94..06fce6e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1431,
+/**/
     1430,
 /**/
     1429,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 6c43ad2..8b58d96 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -2638,6 +2638,11 @@
 	    semsg(_(e_missing_dict_comma), *arg);
 	    goto failret;
 	}
+	if (IS_WHITE_OR_NUL(*whitep))
+	{
+	    semsg(_(e_no_white_before), ",");
+	    return FAIL;
+	}
 	whitep = *arg + 1;
 	*arg = skipwhite(*arg + 1);
     }