patch 8.2.3317: Vim9: No error for missing white space before return type

Problem:    Vim9: No error for missing white space before return type.
Solution:   Check for white space. (closes #8733)
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 5704511..de7b980 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -1429,6 +1429,27 @@
         'defcompile'], 'E1003:')
   delfunc! g:Func
 
+  CheckScriptFailure([
+        'def Func():number',
+        'return 123',
+        'enddef',
+        'defcompile'], 'E1069:')
+  delfunc! g:Func
+
+  CheckScriptFailure([
+        'def Func() :number',
+        'return 123',
+        'enddef',
+        'defcompile'], 'E1059:')
+  delfunc! g:Func
+
+  CheckScriptFailure([
+        'def Func() : number',
+        'return 123',
+        'enddef',
+        'defcompile'], 'E1059:')
+  delfunc! g:Func
+
   CheckScriptFailure(['def Func(): list', 'return []', 'enddef'], 'E1008:')
   delfunc! g:Func
   CheckScriptFailure(['def Func(): dict', 'return {}', 'enddef'], 'E1008:')