fix: improve error message formatting in setSynthVolume

[CodeBySayak]

Description

This PR fixes a malformed error message in the setSynthVolume method within js/turtleactions/VolumeActions.js.

The Problem

When the setSynthVolume function fails to identify a synthesizer or instrument name, it attempts to display an error message to the user. However, the existing code was using the synth variable—which is explicitly null at that point in the logic—instead of the actual input string (synthname). Additionally, the message lacked a space and proper localization support.

Original Buggy Output: nullnot found

Changes

• Updated the error message to use synthname (the actual user-provided input).
• Added a space for readability.
• Wrapped the "not found" text in the _() translation helper to ensure it is correctly localized for all users.

Testing

• Verified that unrecognized instrument names now trigger a readable and properly formatted error alert identifying exactly which input was not found.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature
• Breaking change
• Documentation update

closes #6697

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Failed Tests:

phrasemaker.test.js
VolumeActions.test.js

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Failed Tests:

phrasemaker.test.js

[Ashutoshx7]

hy jest is faling take a look

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Failed Tests:

phrasemaker.test.js

[Ashutoshx7]

jest faling still

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

Coverage: Coverage summary unavailable

[CodeBySayak]

@Ashutoshx7 can you review again I have passed jest tests

[walterbender]

Please put the phrasemaker changes into a separate PR

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Coverage: Coverage summary unavailable

Failed Tests:

phrasemaker.test.js

[github-actions]

This PR has merge conflicts with master.

Please rebase your branch:

# Add upstream remote (one-time setup)
git remote add upstream https://github.com/sugarlabs/musicblocks.git

# Fetch latest master and rebase
git fetch upstream
git rebase upstream/master

# Resolve any conflicts, then:
git push --force-with-lease origin YOUR_BRANCH

Tip: Enable "Allow edits from maintainers" on this PR so we can auto-rebase for you next time. This only grants access to your PR branch. Your fork's other branches are not affected.

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Coverage: Coverage summary unavailable

Failed Tests:

phrasemaker.test.js

[github-actions]

Merge conflicts resolved. Ready for review.

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Coverage: Statements: 41.9% | Branches: 34.79% | Functions: 46.55% | Lines: 42.3%

Failed Tests:

phrasemaker.test.js