fix(xo-web/vm/disks): don't pass null to Size component (#4811)

Fixes support#2181

- `vdi.size` should always be defined
- `null` was passed when `vdi.size` was `0`

packages/xo-web/src/common/editable/index.js

@@ -490,7 +490,8 @@ export class XoSelect extends Editable {
 
 export class Size extends Editable {
   static propTypes = {
-    value: PropTypes.number.isRequired,
+    value: PropTypes.oneOfType([PropTypes.number, PropTypes.oneOf([null])])
+      .isRequired,
   }
 
   get value() {
@@ -498,7 +499,15 @@ export class Size extends Editable {
   }
 
   _renderDisplay() {
-    return this.props.children || formatSize(this.props.value)
+    if (this.props.children !== undefined) {
+      return this.props.children
+    }
+
+    if (this.props.value != null) {
+      return formatSize(this.props.value)
+    }
+
+    return null
   }
 
   _saveIfUnfocused = () => {

packages/xo-web/src/xo-app/vm/tab-disks.js

@@ -2,6 +2,7 @@ import _, { messages } from 'intl'
 import ActionButton from 'action-button'
 import Component from 'base-component'
 import copy from 'copy-to-clipboard'
+import defined from '@xen-orchestra/defined'
 import HTML5Backend from 'react-dnd-html5-backend'
 import Icon from 'icon'
 import IsoDevice from 'iso-device'
@@ -131,7 +132,7 @@ const COLUMNS_VM_PV = [
   {
     itemRenderer: ({ vdi }) => (
       <Size
-        value={vdi.size || null}
+        value={defined(vdi.size, null)}
         onChange={size => editVdi(vdi, { size })}
       />
     ),