Fix duplicate listener name collision between DuplicateBlock and Arpe…

[Ady0333]

Summary

This PR fixes a listener name collision between DuplicateBlock and ArpeggioBlock that caused silent block-graph corruption when one was nested inside the other. Both blocks constructed their teardown listener name as "_duplicate_" + turtle, and since setTurtleListener() stores listeners in a flat dictionary keyed by this string, the inner block registration overwrote the outer block’s listener. When the outer DuplicateBlock clamp ended, its teardown never executed, leaving connectionStore[turtle][duplicateBlk] populated and permanently corrupting the block graph across runs.

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Impact

When nesting Arpeggio inside Duplicate notes (or vice versa), the outer block’s cleanup was silently swallowed. This caused connection rewiring performed by DuplicateBlock to never be restored, leading to progressively broken playback behavior across runs. The corruption persisted until page reload and produced no visible runtime error, making it especially misleading in classroom usage.

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Steps to Reproduce

1. Open Music Blocks.
2. Create: Start → Arpeggio (Cm) clamp → Duplicate notes (2×) clamp → Note 1/4.
3. Click Run.
4. Stop and Run again.

Observed: incorrect duplication behavior and progressive corruption across runs.
Expected: each clamp restores its original connections after execution.

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Root Cause

Both blocks used the identical listener key:

const listenerName = "_duplicate_" + turtle;
When nested, the second setTurtleListener() call evicted the first listener, so the outer teardown callback was permanently lost.

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Fix

Append blk to the listener name so each block instance has a unique teardown listener, matching the convention used by other clamp blocks.

// FlowBlocks.js
- const listenerName = "_duplicate_" + turtle;
+ const listenerName = "_duplicate_" + turtle + "_" + blk;

// IntervalsBlocks.js
- const listenerName = "_duplicate_" + turtle;
+ const listenerName = "_duplicate_" + turtle + "_" + blk;

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Scope

Two-line change in:

• js/blocks/FlowBlocks.js
• js/blocks/IntervalsBlocks.js

No logic changes, no API changes, no new state introduced.

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Verification

Nested Duplicate and Arpeggio blocks now clean up correctly.
connectionStore is restored after execution.
Multiple runs do not accumulate corruption.
Lint and tests pass.

[Ady0333]

@vanshika2720 and @walterbender , please review this pr once.

[github-actions]

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

[github-actions]

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