fix(solvers): prevent crash on empty connections array

[rudra496]

Summary

Fixes #657.

This PR adds safety guards to ensure solvers handle empty or undefined connection arrays (\directConnections: [],
etConnections: []) without throwing uncaught exceptions.

Changes

1. Added nullish coalescing to \getConnectivityMapsFromInputProblem.ts\ for \directConnections\ and
   etConnections.
2. Added nullish coalescing to \MspConnectionPairSolver.ts\ across \chips, \pins, \directConnections, and
   etConnections.
3. Created \ ests/solvers/SchematicTracePipelineSolver/empty-connections-guard.test.ts\ verifying that solving an \InputProblem\ with empty connection arrays succeeds cleanly.

Verification

• \�un test tests/solvers/SchematicTracePipelineSolver/empty-connections-guard.test.ts\ (2/2 passing).

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Project	Deployment	Actions	Updated (UTC)
schematic-trace-solver	Ready	Preview	Aug 15, 2026 3:40pm

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Cover omitted connection arrays in the regression test

This test still supplies both connection arrays, so it does not exercise the undefined case named by the test and commit; the same empty-array inputs would have been safe before this patch because for ... of [] is valid. When a pipeline caller actually omits these fields, the new local guards let MspConnectionPairSolver proceed, but downstream code such as NetLabelPlacementSolver.computeOverlappingSameNetTraceGroups() still dereferences this.inputProblem.directConnections/netConnections, so the crash can remain undetected. Please omit these fields in the regression test or normalize them on the input object before later solvers see it.

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