Report a login failure from the CLI as a readable error

[adityasingh2400]

Fixes #3523.

Creating a dataset without valid credentials produced two unhelpful outcomes, both visible in the tracebacks on the issue.

First, createDataset stringified the whole GraphQL errors array, so the one line that matters, "You must be logged in to create a dataset.", was buried in a server side stacktrace.

Second, a response carrying data.createDataset: null with no top level errors made createDataset resolve to undefined despite its Promise<string> type. That only failed much later as TypeError: Path must be a string, received "undefined" from the join(repoDir, datasetId) in upload.ts, which points the user at a path problem rather than at their credentials.

Only the GraphQL messages are kept now. An authentication failure raises LoginError naming the command that fixes it, and a response with no accession number is rejected where it happens instead of turning into a path error later. getLatestSnapshotVersion shares the same handling. The upload command prints that message and stops rather than throwing an uncaught error.

Reverting graphq.ts and upload.ts gives 1 passed and 4 failed: the no accession number case resolved undefined without throwing, the missing credentials case gave a ResponseError instead of a LoginError, and both message filtering cases returned the raw JSON array. After, the full CLI suite is green at 41 passed across 12 steps, with deno fmt and deno lint clean.

One note for anyone running this locally. cli/deno.json has "minimumDependencyAge": {"exclude": [...]}, which deno 2.6.10 rejects with Unsupported "minimumDependencyAge" object. Caused by: missing field 'age'. I dropped the key locally to run the tests and restored it before committing, so this branch does not touch it. CI pins deno-version: v2.x, so this may start biting soon.

Disclosure: this change was prepared with AI assistance. I have reviewed and tested it.

[codecov]

Codecov Report

❌ Patch coverage is 71.87500% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 49.04%. Comparing base (2ac78fc) to head (2783e26).
⚠️ Report is 22 commits behind head on master.

Files with missing lines	Patch %	Lines
cli/src/graphq.ts	78.57%	4 Missing and 2 partials ⚠️
cli/src/commands/upload.ts	25.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4053      +/-   ##
==========================================
+ Coverage   48.89%   49.04%   +0.15%     
==========================================
  Files         686      686              
  Lines       38069    38093      +24     
  Branches     1894     1906      +12     
==========================================
+ Hits        18615    18684      +69     
+ Misses      19293    19242      -51     
- Partials      161      167       +6     

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[nellh]

Thanks for your contribution.