git flow release start fails when version argument is missing (regression from AVH)

[Alcarmor]

git-flow-next version $\rightarrow$ 1.0.0
platform $\rightarrow$ windows

Description
In the original git-flow (AVH edition), providing a version argument to git flow release start is not strictly mandatory if a version filter/hook is configured to determine the next version automatically.

In git-flow-next, the command currently throws an error if the branch name (version) is not explicitly provided as a positional argument.

Expected Behavior
The tool should attempt to retrieve the version via the configured version filter before failing. If the filter successfully returns a version, the command should proceed without requiring manual input.

Actual Behavior
The command exits with an error if the argument is missing, ignoring any logic that might derive the version programmatically.

Comparison

• Git-flow (AVH): Checks for the version argument $\rightarrow$ if missing, runs the version filter $\rightarrow$ if still missing, returns error.
• Git-flow-next: Checks for the branch name argument $\rightarrow$ if missing, returns error immediately.

Proposed Solution
Modify the argument validation logic in release start to allow an empty version/branch name argument initially, triggering the version retrieval logic (hooks/filters) before deciding whether to stop execution. This would restore parity with the AVH workflow and support automated versioning tools.