Fix Power BI Costs query type mismatch on VCPUs/vCores cast

[Michael Flanakin (flanakin)]

🛠️ Description

The storage-based Power BI Costs query cast tmp_VMvCPUs/tmp_SQLvCores (values extracted from the free-form x_SkuDetails JSON blob) straight to Int64.Type via Table.TransformColumnTypes. That blob's shape varies by charge type (VM usage, Marketplace/SaaS purchase, reservation purchase, etc.), so on a row where the VCPUs/vCores field isn't a clean number, the cast produced an Error value instead of throwing during query evaluation. When that error-valued cell was loaded into the model as an Int64 column, Power BI surfaced it during refresh as:

OLE DB or ODBC error: Type mismatch (DISP_E_TYPEMISMATCH 0x80020005)

A single month often has no such rows, so it refreshes fine; a full-year refresh pulls in the row that trips it, matching the report.

This switches the cast to Table.TransformColumns with a try ... otherwise null guard, mirroring the existing defensive pattern used for x_SkuTerm (#2175) — an unparseable or missing value now degrades to null instead of failing the whole refresh.

Fixes #2297

📷 Screenshots

N/A (Power Query/M change, no visual change)

📋 Checklist

🔬 How did you test this change?

• 🤏 Lint tests
• 🤞 PS -WhatIf / az validate
• 👍 Manually deployed + verified
• 💪 Unit tests
• 🙌 Integration tests

No automated test coverage exists for Power Query/M logic in this repo, and I don't have a Power BI Desktop environment connected to the reporter's storage account to reproduce the failure live, so this hasn't been verified against real failing data. I read through the full Costs.tmdl M query and confirmed the Table.TransformColumnTypes call at the reported line is the only unguarded numeric cast on a value sourced from the SKU details JSON blob, and confirmed the replacement Table.TransformColumns syntax is valid M.

📦 Deploy to test?

• Hubs + ADX (managed)
• Hubs + Fabric (manual) — URI:
• Hubs (manual)
• Hubs (no data)
• Workbooks
• Alerts

🙋‍♀️ Do any of the following that apply?

• 🤏 The change is less than 20 lines of code.

📑 Did you update docs/changelog.md?

• ✅ Updated changelog (required for dev PRs)

📖 Did you update documentation?

• ✅ Public docs in docs (required for dev)
• ✅ Public docs in docs-mslearn (required for dev)
• ✅ Internal dev docs in docs-wiki (required for dev)
• ✅ Internal dev docs in src (required for dev)
• ❎ Docs not needed (small/internal change)

🤖 Generated with Claude Code

[microsoft-github-policy-service]

@Michael Flanakin (@flanakin), thanks for the PR. It looks like you forgot to indicate whether the documentation was updated as part of the PR. Please edit the PR to select (x) the appropriate items in the checklist. This PR will be blocked until one of the values is selected.

[microsoft-github-policy-service]

@Michael Flanakin (@flanakin), thanks for the PR. It looks like you forgot to indicate whether the documentation was updated as part of the PR. Please edit the PR to select (x) the appropriate items in the checklist. This PR will be blocked until one of the values is selected.