Coding error in usdchecker when using internal references

[hinton-mgi]

Description of Issue

Instead of printing any compliance issues and gracefully exiting, usdchecker fails with an error for some usd files. I believe this particular problem occurs when the usd file contains internal references.

Steps to Reproduce

1. Create test.usda with the following contents:

#usda 1.0

def Sphere "sphere"
{
}

def "clone" (
    prepend references = </sphere>
)
{
}

2. run usdchecker test.usda
3. My result was:

Traceback (most recent call last):
  File "D:\Testing\USD-sdk\bin\usdchecker", line 149, in <module>
    sys.exit(main())
  File "D:\Testing\USD-sdk\bin\usdchecker", line 118, in main
    checker.CheckCompliance(inputFile)
  File "D:\Testing\USD-sdk\lib\python\pxr\UsdUtils\complianceChecker.py", line 969, in CheckCompliance
    UsdUtils.ComputeAllDependencies(Sdf.AssetPath(inputFile))
pxr.Tf.ErrorException:
        Error in 'pxrInternal_v0_22__pxrReserved__::SdfComputeAssetPathRelativeToLayer' at line 92 in file D:\Testing\USD\pxr\usd\sdf\layerUtils.cpp : 'Layer path is empty'

System Information (OS, Hardware)

Windows 10

Package Versions

USD built from dev branch, HEAD at commit a470570

Build Flags

PXR_ENABLE_METAL_SUPPORT=FALSE
PXR_ENABLE_VULKAN_SUPPORT=FALSE
PXR_ENABLE_PTEX_SUPPORT=FALSE
PXR_USE_PYTHON_3=ON

[spiffmon]

Thanks for reporting, @hinton-mgi - I can't believe this has gone undetected so long! For the fixer: I investigated, and think the culprit is _FileAnalyzer::_ProcessReferences(), though _FileAnalyzer::_RemapRefOrPayload() and _FileAnalyzer::_ProcessPayloads() are similarly unguarded against internal references.

[sunyab]

Filed as internal issue #USD-7424