[FIX] TableComputedStylePlugin: skip table style for invalid pivot

[dhrp-odoo]

Description:

Pivot table style computation could call pivot runtime getters while an Odoo pivot was temporarily invalid/loading. Guard the pivot before reading its table structure and return no table style until it is valid again.

Task: 6306263

review checklist

• feature is organized in plugin, or UI components
• support of duplicate sheet (deep copy)
• in model/core: ranges are Range object, and can be adapted (adaptRanges)
• in model/UI: ranges are strings (to show the user)
• undo-able commands (uses this.history.update)
• multiuser-able commands (has inverse commands and transformations where needed)
• new/updated/removed commands are documented
• exportable in excel
• translations (_t("qmsdf %s", abc))
• unit tested
• clean commented code
• track breaking changes
• doc is rebuild (npm run doc)
• status is correct in Odoo

[robodoo]