**Steps to replicate the issue** (include links if applicable):
When adding values to combobox field, saving the form, then edits the form again, the value replaced with 0
Here's minimal wikitext to check this
```
<noinclude>
This form is being used to create my_page pages for use as Main pages in our system
{{#forminput:form={{PAGENAME}}|button text=Create my page|placeholder=Page name}}
</noinclude>
<includeonly>
<div id="wikiPreview" style="display: none; padding-bottom: 25px; margin-bottom: 25px; border-bottom: 1px solid #AAAAAA;"></div>
==Page==
{{{for template|my_page}}}
{{{field|parts 1|holds template}}}
{{{end template}}}
{{{for template|part 1|multiple|add button text=Add part|embed in field=my_page[parts 1]|display=table}}}
{{{field|title_section|input type=combobox|label=part title (can be the target page name)|values from namespace=Main}}}
{{{field|subtitle|label=part content}}}
{{{end template}}}
__NOTOC__ __NOEDITSECTION__
```
- create form with this wikitext
- create page with this form, add value to one or more section_title fields.
- Save it.
- Check in `?action=edit` - value is OK
- Edit the page with the form.
- You dont have to change something
- Save it
- Check in `?action=edit `
- `section_title=0`
**What happens?**:
value is becoming 0
**What should have happened instead?**:
value presists
**Software version** :
- MW 1.40.3
- PageForms commit: be96c99fe44dcaa2d4764ee3a8eaca47d443a339
**Other information**
The data I've mange to grab:
* this is PHP bug: the source code of HTML rendering input with value="0"
* while editing the page with the form (second time) `$cur_value` of the problematic field, for example in `PFFormPrinter::formHTML` is **an array** of `[0 => 'FIELD_VALUE']`. I don't have enough knowledge if this as intended or not.
* If I'm understanding well, this is part of `$gridValues` var