json-lexer: fix conflict with mingw32 ERROR definition

The name ERROR is too generic, it conflicts with mingw32 ERROR definition.

Replace ERROR with IN_ERROR.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/json-lexer.c b/json-lexer.c
index c736f42..65c9720 100644
--- a/json-lexer.c
+++ b/json-lexer.c
@@ -28,7 +28,7 @@
  */
 
 enum json_lexer_state {
-    ERROR = 0,
+    IN_ERROR = 0,
     IN_DQ_UCODE3,
     IN_DQ_UCODE2,
     IN_DQ_UCODE1,
@@ -150,7 +150,7 @@
     /* Zero */
     [IN_ZERO] = {
         TERMINAL(JSON_INTEGER),
-        ['0' ... '9'] = ERROR,
+        ['0' ... '9'] = IN_ERROR,
         ['.'] = IN_MANTISSA,
     },
 
@@ -302,7 +302,7 @@
             lexer->token = qstring_new();
             new_state = IN_START;
             break;
-        case ERROR:
+        case IN_ERROR:
             return -EINVAL;
         default:
             break;