fix Bytearray.insert, Bytearray.remove

dev/tests/bytearray.lua

@@ -13,3 +13,12 @@ end
 
 Bytearray.remove(arr, 2)
 assert(#arr == 9)
+
+Bytearray.insert(arr, {5, 3, 6})
+
+assert(#arr == 12)
+Bytearray.insert(arr, 2, 8)
+assert(#arr == 13)
+for i=1,10 do
+    assert(arr[i] == 10 - i)
+end

res/modules/internal/bytearray.lua

@@ -48,7 +48,8 @@ local function append(self, b)
 end
 
 local function insert(self, index, b)
-    if index == nil then
+    if b == nil then
+        b = index
         index = self.size + 1
     end
     if index <= 0 or index > self.size + 1 then
@@ -81,7 +82,7 @@ local function remove(self, index, elems)
     if index + elems > self.size then
         elems = self.size - index + 1
     end
-    for i=index, self.size - elems do
+    for i=index - 1, self.size - elems - 1 do
         self.bytes[i] = self.bytes[i + elems]
     end
     self.size = self.size - elems