[arsalanyavari]

What this PR does

Fixes --scale flag validation in docker compose up / create when an empty service name is passed (e.g. --scale "=2").

Currently, applyScaleOpts only checks !ok || val == "", missing the empty service name check (name == ""). As a result, passing an empty service name passes flag validation and fails later during service lookup with no such service: : not found.

This change adds name == "" to the validation check in applyScaleOpts, aligning it with cmd/compose/scale.go to reject the syntax upfront with a clear CLI error:
invalid --scale option "=2". Should be SERVICE=NUM.

Related issue

Fixes #14480

Changes made

• Added name == "" check to applyScaleOpts in cmd/compose/create.go (consistent with cmd/compose/scale.go).
• Added test assertion for empty service name ("=2") to existing TestApplyScaleOpt in cmd/compose/up_test.go.

Testing done

• Unit tests pass: make test

• E2E tests pass: make e2e-compose or make e2e-compose-standalone

• Linting passes: make lint

• Code formatted: make fmt

• Manually tested (describe):

  • Before:

    $ docker compose up --dry-run --scale "=2"
    no such service: : not found
    

  • After:

    $ ./bin/build/docker-compose -f compose.yaml up --dry-run --scale "=2"
    invalid --scale option "=2". Should be SERVICE=NUM
    

  • Verified valid scale options still work as expected (--scale "web=2").

AI tool used (if applicable)

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