patch 8.0.0216: decoding js style json may fail

Problem:    When decoding JSON with a JS style object the JSON test may use a
            NULL pointer. (Coverity)
Solution:   Check for a NULL pointer.

Author: brammool

src/json.c

@@ -629,10 +629,13 @@ json_decode_item(js_read_T *reader, typval_T *res, int options)
 	    key = p = reader->js_buf + reader->js_used;
 	    while (*p != NUL && *p != ':' && *p > ' ')
 		++p;
-	    cur_item->v_type = VAR_STRING;
-	    cur_item->vval.v_string = vim_strnsave(key, (int)(p - key));
+	    if (cur_item != NULL)
+	    {
+		cur_item->v_type = VAR_STRING;
+		cur_item->vval.v_string = vim_strnsave(key, (int)(p - key));
+		top_item->jd_key = cur_item->vval.v_string;
+	    }
 	    reader->js_used += (int)(p - key);
-	    top_item->jd_key = cur_item->vval.v_string;
 	}
 	else
 	{
@@ -1053,7 +1056,8 @@ json_decode(js_read_T *reader, typval_T *res, int options)
 
 /*
  * Decode the JSON from "reader" to find the end of the message.
- * "options" can be JSON_JS or zero;
+ * "options" can be JSON_JS or zero.
+ * This is only used for testing.
  * Return FAIL if the message has a decoding error.
  * Return MAYBE if the message is truncated, need to read more.
  * This only works reliable if the message contains an object, array or

src/json_test.c

@@ -107,6 +107,12 @@ test_decode_find_end(void)
     reader.js_buf = (char_u *)"  {   ";
     assert(json_find_end(&reader, 0) == MAYBE);
 
+    /* JS object with white space */
+    reader.js_buf = (char_u *)"  {  a  :  123  }  ";
+    assert(json_find_end(&reader, JSON_JS) == OK);
+    reader.js_buf = (char_u *)"  {  a  :   ";
+    assert(json_find_end(&reader, JSON_JS) == MAYBE);
+
     /* array without white space */
     reader.js_buf = (char_u *)"[\"a\",123]";
     assert(json_find_end(&reader, 0) == OK);

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    216,
 /**/
     215,
 /**/