patch 8.2.2139: Vim9: unreachable code in assignment

Problem:    Vim9: unreachable code in assignment.
Solution:   Don't check "new_local" when "has_index" is set.  Add test for
            wrong type of list index.

src/testdir/test_vim9_assign.vim

@@ -326,6 +326,18 @@ def Test_assign_index()
   END
   CheckDefFailure(lines, 'E1012: Type mismatch; expected number but got dict<unknown>', 3)
 
+  lines =<< trim END
+    var lines: list<string>
+    lines['a'] = 'asdf'
+  END
+  CheckDefFailure(lines, 'E39:', 2)
+
+  lines =<< trim END
+    var lines: string
+    lines[9] = 'asdf'
+  END
+  CheckDefFailure(lines, 'E1141:', 2)
+
   # list of dict
   var ld: list<dict<number>>
   ld[0] = {}

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2139,
 /**/
     2138,
 /**/

src/vim9compile.c

@@ -5856,8 +5856,6 @@ compile_assignment(char_u *arg, exarg_T *eap, cmdidx_T cmdidx, cctx_T *cctx)
 	    int r;
 
 	    // Compile the "idx" in "var[idx]" or "key" in "var.key".
-	    if (new_local)
-		--cctx->ctx_locals.ga_len;
 	    p = var_start + varlen;
 	    if (*p == '[')
 	    {
@@ -5877,8 +5875,6 @@ compile_assignment(char_u *arg, exarg_T *eap, cmdidx_T cmdidx, cctx_T *cctx)
 
 		r = generate_PUSHS(cctx, key);
 	    }
-	    if (new_local)
-		++cctx->ctx_locals.ga_len;
 	    if (r == FAIL)
 		goto theend;