When a tool fails, attempt to show lines that contain error information

[JesseCol]

Before this change, when there's an error with a tool it's unclear why it's happening. Users must know to re-run with "--verbose" option to see the error text.

After this change, here's what the output looks like when there's an error:

...(cut lines of output)...
Processing "\\?\D:\temp\qwe\.gitignore" as a payload file.  Its path in the package will be ".gitignore".
Processing "\\?\D:\temp\qwe\winapp.yaml" as a payload file.  Its path in the package will be "winapp.yaml".
Processing "\\?\D:\temp\qwe\qwe.msix" as a payload file.  Its path in the package will be "qwe.msix".
Processing "\\?\D:\temp\qwe\pri.resfiles" as a payload file.  Its path in the package will be "pri.resfiles".
Processing "\\?\D:\temp\qwe\priconfig.xml" as a payload file.  Its path in the package will be "priconfig.xml".
Processing "\\?\D:\temp\qwe\resources.pri" as a payload file.  Its path in the package will be "resources.pri".
MakeAppx : error: Error info: error C00CE014: App manifest validation error: The app manifest must be valid as per schema: Line 14, Column 4, Reason: Element '{http://schemas.microsoft.com/appx/manifest/foundation/windows10}Ientity' is unexpected according to content model of parent element '{http://schemas.microsoft.com/appx/manifest/foundation/windows10}Package'.
Expecting: {http://schemas.microsoft.com/appx/manifest/foundation/windows10}Identity, {http://schemas.microsoft.com/appx/manifest/foundation/windows10}Properties, {http://schemas.microsoft.com/appx/manifest/foundation/windows10}Dependencies.

MakeAppx : error: Package creation failed.
MakeAppx : error: 0x80080204 - The specified package format is not valid: The package manifest is not valid.

❌ Failed to create MSIX package: Failed to create MSIX package: makeappx.exe execution failed with exit code 1

[nmetulev]

Would it be possible to only include the error lines and not include any of the processing lines (unless --verbose is used)?

[azchohfi]

The tools in winsdk are quite old, and I don't believe they use stdout/stderr properly, or at least some of them don't. Therefore, we can't make this assumption, so the answer is no.

[JesseCol]

Would it be possible to only include the error lines and not include any of the processing lines (unless --verbose is used)?

That was my first attempt!

How about this:

1. For tools we've tested and are confident we understand their error output (like signtool), output ONLY the error lines.
2. For other tools, output everything.
3. In the (1) case, print a message about how the user can see full output on the next run.