Handle version 0 correctly during validation

[AlekseyManetov]

Proposed Changes

Closes #176

The issue was in wrong template validation for case when template without version and with '0' version was assumed as duplicates. In this case template with '0' version was not added to the valid templates list and wasn't proposed for the update. For all other cases, e.g. template without version and template with version > 0, update logic worked as expected.

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[Copilot]

Pull request overview

This PR fixes a bug in template validation where templates without a version and templates with version 0 were incorrectly treated as duplicates. Previously, the code used template.version || '_' which converted the falsy value 0 to '_', causing version 0 templates to collide with unversioned templates. The fix changes this to use isNil(template.version) ? '_' : template.version, which only treats null and undefined as "no version" while preserving 0 as a valid version value.

Changes:

• Updated version checking logic in both element-templates and cloud-element-templates validators to use isNil() instead of falsy checks
• Added test cases to verify templates with no version and version 0 are treated as distinct
• Updated test fixtures and BPMN diagrams to support the new test scenarios

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/element-templates/Validator.js	Updated _validateTemplate to use isNil() for version checking; imported isNil from min-dash
src/cloud-element-templates/Validator.js	Updated _validateTemplate to use isNil() for version checking; imported isNil from min-dash
test/spec/element-templates/Validator.spec.js	Added test case verifying templates with no version and version 0 are accepted as different versions
test/spec/cloud-element-templates/Validator.spec.js	Added test case verifying templates with no version and version 0 are accepted as different versions
test/spec/cloud-element-templates/fixtures/falsy-version.json	Updated fixture to include both a template without version and a template with version 0
test/spec/cloud-element-templates/fixtures/complex.bpmn	Added a task element referencing the falsy-template for integration testing
CHANGELOG.md	Added entry documenting the bug fix

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[philippfromme]

Looks good! ✅ I simplified the changelog entry a little bit and adjusted the commit messages. We always want to make sure we mention the issue in the commit message (e.g. Closes #123).