Handle emoji availability deserialization failures.

Signal/src/util/Emoji/Emoji+Available.swift

@@ -33,6 +33,12 @@ extension Emoji {
             }
 
             let availableMap = availableStore.allBoolValuesMap(transaction: transaction)
+            guard !availableMap.isEmpty else {
+                Logger.info("Re-building emoji availability cache. Cache could not be loaded.")
+                uncachedEmoji = Emoji.allCases
+                return
+            }
+
             for emoji in Emoji.allCases {
                 if let available = availableMap[emoji.rawValue] {
                     availableCache[emoji] = available
@@ -54,6 +60,7 @@ extension Emoji {
 
         if uncachedAvailability.count > 0 || iosVersionNeedsUpdate {
             SDSDatabaseStorage.shared.write { transaction in
+                availableStore.removeAll(transaction: transaction)
                 for (emoji, available) in uncachedAvailability {
                     availableStore.setBool(available, key: emoji.rawValue, transaction: transaction)
                 }

SignalServiceKit/src/Storage/Database/SDSKeyValueStore.swift

@@ -410,9 +410,14 @@ public class SDSKeyValueStore: NSObject {
             WHERE \(SDSKeyValueStore.collectionColumn.columnName) == ?
             """
 
-            return try! PairRecord.fetchAll(grdbTransaction.database,
-                                            sql: sql,
-                                            arguments: [collection])
+            do {
+                return try PairRecord.fetchAll(grdbTransaction.database,
+                                               sql: sql,
+                                               arguments: [collection])
+            } catch {
+                owsFailDebug("Error: \(error)")
+                return []
+            }
         }
     }