fix(scripts): make the last two self-tests prove they reached their verdict (#15123)

`check-type-check-coverage.mjs` and `bare-root-worklist.mjs` were the last two
gates in `scripts/**` that the census reads as DEFEATED: an early `return`
anywhere above the verdict line printed NOTHING and still exited 0, so a
self-test that never finished reported as one that passed.

Both dispatches DISCARD the self-test's return value
(`selfTest(); process.exit(0);` and `if (--self-test) selfTest(); else report()`),
so the sentinel spelling landed in PRs #14479 / #14853 is the fitting form for
each: `SELF_TEST_VERDICT` returned only after the success line, compared at the
dispatch, which refuses anything else with exit 1. Nothing inside either
self-test body changes.

Part of #13798


Claude-Session: https://claude.ai/code/session_012zGPuVVX3deAx9LdjK8jCk

Co-authored-by: Claude <noreply@anthropic.com>

Author: claude[bot]

scripts/check-type-check-coverage.mjs

@@ -3794,6 +3794,12 @@ function observed() {
   };
 }
 
+// Returned by `selfTest()` only after its verdict is printed. The dispatch
+// refuses anything else: a `return` that leaves the function above that line
+// prints nothing and still exits 0 — a self-test that never finished, reported
+// as one that passed (#13798).
+const SELF_TEST_VERDICT = 'check-type-check-coverage self-test reached its verdict';
+
 /**
  * The ledger semantics are the one part of this gate that can be wrong while
  * every package is right -- an evaluate() that under-reports waves the next
@@ -5657,10 +5663,19 @@ function selfTest() {
       `${planCases.length + rewriteCases.length + roundTripCases.length} auto-lowering case(s) + ` +
       `${REFUSING.length * 2 + 1 + exitCodeCases.length + textCases.length} exit-code case(s) hold.`,
   );
+
+  return SELF_TEST_VERDICT;
 }
 
 if (process.argv.includes('--self-test')) {
-  selfTest();
+  if (selfTest() !== SELF_TEST_VERDICT) {
+    console.error(
+      '\n✗ check:type-check-coverage self-test: selfTest() returned without reaching its verdict,\n'
+        + 'so no success line was printed. Exiting 0 here would report a self-test\n'
+        + 'that never finished as a self-test that passed.\n',
+    );
+    process.exit(1);
+  }
   process.exit(0);
 }
 

scripts/pm/bare-root-worklist.mjs

@@ -1396,6 +1396,12 @@ function report({ wide = false } = {}) {
   }
 }
 
+// Returned by `selfTest()` only after its verdict is printed. The dispatch
+// refuses anything else: a `return` that leaves the function above that line
+// prints nothing and still exits 0 — a self-test that never finished, reported
+// as one that passed (#13798).
+const SELF_TEST_VERDICT = 'bare-root-worklist self-test reached its verdict';
+
 function selfTest() {
   const failures = [];
   const t = (label, ok) => { if (!ok) failures.push(label); };
@@ -1698,9 +1704,19 @@ function selfTest() {
       + '(#14695) are well-formed, disjoint from TRIAGE, contribute no hint of their own, and share '
       + 'one base commit.',
   );
+
+  return SELF_TEST_VERDICT;
 }
 
 if (isEntrypoint(import.meta.url)) {
-  if (process.argv.includes('--self-test')) selfTest();
-  else report({ wide: process.argv.includes('--wide') });
+  if (process.argv.includes('--self-test')) {
+    if (selfTest() !== SELF_TEST_VERDICT) {
+      console.error(
+        '\n✗ bare-root-worklist self-test: selfTest() returned without reaching its verdict,\n'
+          + 'so no success line was printed. Exiting 0 here would report a self-test\n'
+          + 'that never finished as a self-test that passed.\n',
+      );
+      process.exit(1);
+    }
+  } else report({ wide: process.argv.includes('--wide') });
 }