handleSize seems to be ignored on Custom spaces, always 5px

**Describe the bug**
A clear and concise description of what the bug is.

**To Reproduce**
<Spaces.Custom handleSize={1} >{children}</Spaces.Custom>

**Expected behavior**
Resizer should have a width of 1px when passing `handleSize={1}`.

**Desktop (please complete the following information):**
 - OS: Windows 7
 - Browser Electron
 - Version 8.5.x