patch 8.2.2115: Vim9: some errors not tested for; dead code

Problem:    Vim9: some errors not tested for; dead code.
Solution:   Add a test.  Remove dead code.

src/testdir/test_vim9_assign.vim

@@ -1045,6 +1045,9 @@ def Test_var_declaration()
     s:name = 'prefixed'
     g:var_prefixed = s:name
 
+    const FOO: number = 123
+    assert_equal(123, FOO)
+
     var s:other: number
     other = 1234
     g:other_var = other
@@ -1087,6 +1090,10 @@ def Test_var_declaration_fails()
     var 9var: string
   END
   CheckScriptFailure(lines, 'E475:')
+
+  CheckDefFailure(['var foo.bar = 2'], 'E1087:')
+  CheckDefFailure(['var foo[3] = 2'], 'E1087:')
+  CheckDefFailure(['const foo: number'], 'E1021:')
 enddef
 
 def Test_var_type_check()

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2115,
 /**/
     2114,
 /**/

src/vim9compile.c

@@ -5705,12 +5705,7 @@ compile_assignment(char_u *arg, exarg_T *eap, cmdidx_T cmdidx, cctx_T *cctx)
 
 			// without operator check type here, otherwise below
 			if (has_index)
-			{
 			    use_type = member_type;
-			    if (member_type == NULL)
-				// could be indexing "any"
-				use_type = &t_any;
-			}
 			if (need_type(rhs_type, use_type, -1, cctx,
 						      FALSE, is_const) == FAIL)
 			    goto theend;