fix a bug about Json::Path

Author: chason-super

src/lib_json/json_value.cpp

@@ -1504,12 +1504,12 @@ void Path::makePath(const JSONCPP_STRING& path, const InArgs& in) {
           index = index * 10 + ArrayIndex(*current - '0');
         args_.push_back(index);
       }
-      if (current == end || *current++ != ']')
+      if (current == end || *++current != ']')
         invalidPath(path, int(current - path.c_str()));
     } else if (*current == '%') {
       addPathInArg(path, in, itInArg, PathArgument::kindKey);
       ++current;
-    } else if (*current == '.') {
+    } else if (*current == '.' || *current == ']') {
       ++current;
     } else {
       const char* beginName = current;
@@ -1529,7 +1529,7 @@ void Path::addPathInArg(const JSONCPP_STRING& /*path*/,
   } else if ((*itInArg)->kind_ != kind) {
     // Error: bad argument type
   } else {
-    args_.push_back(**itInArg);
+    args_.push_back(**itInArg++);
   }
 }
 
@@ -1544,16 +1544,19 @@ const Value& Path::resolve(const Value& root) const {
     if (arg.kind_ == PathArgument::kindIndex) {
       if (!node->isArray() || !node->isValidIndex(arg.index_)) {
         // Error: unable to resolve path (array value expected at position...
+        return Value::null;
       }
       node = &((*node)[arg.index_]);
     } else if (arg.kind_ == PathArgument::kindKey) {
       if (!node->isObject()) {
         // Error: unable to resolve path (object value expected at position...)
+        return Value::null;
       }
       node = &((*node)[arg.key_]);
       if (node == &Value::nullSingleton()) {
         // Error: unable to resolve path (object has no member named '' at
         // position...)
+        return Value::null;
       }
     }
   }