Annexed files without local content crash validation

[nellh]

trafficstars

This is for the schema validator.

error: Uncaught NotFound: No such file or directory (os error 2), open '/home/nell/Git/crn/datasets/ds000117/sub-01/ses-mri/anat/sub-01_ses-mri_acq-mprage_T1w.nii.gz'
    return Deno.openSync(this._getPath(), openOptions)
                ^
    at Object.openSync (deno:runtime/js/40_files.js:40:21)
    at BIDSFileDeno.#openHandle (file:///home/nell/Git/crn/bids-validator/bids-validator/src/files/deno.ts:108:17)
    at BIDSFileDeno.readBytes (file:///home/nell/Git/crn/bids-validator/bids-validator/src/files/deno.ts:94:36)
    at loadHeader (file:///home/nell/Git/crn/bids-validator/bids-validator/src/files/nifti.ts:5:20)
    at BIDSContext.loadNiftiHeader (file:///home/nell/Git/crn/bids-validator/bids-validator/src/schema/context.ts:155:27)
    at BIDSContext.asyncLoads (file:///home/nell/Git/crn/bids-validator/bids-validator/src/schema/context.ts:185:10)
    at async validate (file:///home/nell/Git/crn/bids-validator/bids-validator/src/validators/bids.ts:77:5)
    at async main (file:///home/nell/Git/crn/bids-validator/bids-validator/src/main.ts:23:24)
    at async file:///home/nell/Git/crn/bids-validator/bids-validator/src/main.ts:41:1

[nellh]

This should probably throw a validation error in this situation but we want a flag to not read file contents that would also avoid this error. Open question, should we automatically ignore missing file contents when we see a git-annex dataset or is that too magic?

[effigies]

Not sure if this is done, so bumping it for your consideration, @nellh.

[nellh]

This is fixed, there could be some improvements to handling the missing content but the important part of not crashing in this situation is handled.