fix(SwingSet): Tolerate absence of a kpid from maybeFreeKrefs

...on suspicion that it absence stems database rollback after a failed delivery

koid absence was already tolerated.

Author: gibson042

packages/SwingSet/src/kernel/kernel.js

@@ -1458,8 +1458,16 @@ export default function buildKernel(
       queueToKref(vatAdminRootKref, method, args, 'logFailure');
     }
 
-    kernelKeeper.processRefcounts();
     const crankNum = kernelKeeper.getCrankNumber();
+    const { lostObjects } = kernelKeeper.processRefcounts();
+    if (lostObjects.length) {
+      console.log(
+        `⚠️ Ignoring lost objects from crankNum ${crankNum}`,
+        lostObjects,
+        message,
+        crankResults,
+      );
+    }
     kernelKeeper.incrementCrankNumber();
     const { crankhash, activityhash } = kernelKeeper.emitCrankHashes();
     finish({

packages/SwingSet/src/kernel/state/kernelKeeper.js

@@ -1614,12 +1614,17 @@ export default function makeKernelKeeper(
   // leaving work for the next delivery.
 
   function processRefcounts() {
+    const lostObjects = [];
     if (enableKernelGC) {
       const actions = new Set();
       for (const kref of maybeFreeKrefs.values()) {
         const { type } = parseKernelSlot(kref);
         if (type === 'promise') {
           const kpid = kref;
+          if (!hasKernelPromise(kpid)) {
+            lostObjects.push(kref);
+            continue;
+          }
           const kp = getKernelPromise(kpid);
           if (kp.refCount === 0) {
             let idx = 0;
@@ -1645,6 +1650,9 @@ export default function makeKernelKeeper(
             // deleted). Message delivery should use that, but not us.
             const ownerKey = `${kref}.owner`;
             let ownerVatID = kvStore.get(ownerKey);
+            if (!ownerVatID) {
+              lostObjects.push(kref);
+            }
             const terminated = terminatedVats.includes(ownerVatID);
 
             // Some objects that are still owned, but the owning vat
@@ -1706,6 +1714,7 @@ export default function makeKernelKeeper(
       addGCActions([...actions]);
     }
     maybeFreeKrefs.clear();
+    return { lostObjects };
   }
 
   function createVatState(vatID, source, options) {