Sentry issues

• MONOREPO-EDITOR-MK — TypeError: Cannot read properties of undefined (reading 'join')
• MONOREPO-EDITOR-MJ — related same-second downstream render failure; this change addresses the shared invalid-update path but does not claim a separate MJ fix.

Root cause

An invalid numeric node update correctly entered the sanitizer, but its warning formatter assumed every runtime NumericSanitizeIssue.path was an array and called .join() unconditionally. That made the error reporter throw inside updateNodesAction, masking the original schema-validation failure and aborting the remaining update batch. NumericSanitizeIssue.path is statically required, and all current sanitizeNumericValue call paths start from [] and extend with array spreads, so no reproducible in-source producer of an undefined path was found; the Sentry payload demonstrates the runtime invariant was nevertheless violated.

What changed

• make numeric issue formatting tolerate null/undefined issue lists and missing/non-array paths, with a final non-throwing fallback
• isolate both message construction and the warning sink so diagnostics can never interrupt node mutation
• add regressions for missing paths and for a batched updateNodes call continuing after schema-invalid numeric data even when warning output throws

Verification

• bun test packages/core/src/store/actions/node-mutation-sanitize.test.ts — PASS: 11 passed, 0 failed
• bun biome lint packages/core/src/store/actions/node-actions.ts packages/core/src/store/actions/node-mutation-sanitize.test.ts — PASS: checked 2 files, no fixes applied
• git diff --check — PASS

This is unverified against production traffic and needs review before merge.