new arrray remove and concat issue fixed

snippets/array-concatenation.md

@@ -3,6 +3,6 @@
 Use `Array.concat()` to concatenate and array with any additional arrays and/or values, specified in `args`.
 
 ```js
-const ArrayConcat = (arr, ...args) => arr.concat(...args); 
+const ArrayConcat = (arr, ...args) => [].concat(arr, ...args); 
 // ArrayConcat([1], [1, 2, 3, [4]]) -> [1, 2, 3, [4]]
 ```

snippets/remove.md

@@ -4,9 +4,11 @@ Remove elements from `arr` that are returns truthy. Use `Array.filter()` to find
 
 ```js
 const remove = (arr, func) =>
+    Array.isArray(arr) ?
     arr.filter(func).reduce((acc, val) => {
         arr.splice(arr.indexOf(val), 1)
         return acc.concat(val);
     }, [])
+    : [];
 //remove([1, 2, 3, 4], n => n % 2 == 0) -> [2, 4]
 ```