diff --git a/packages/crypto/src/__tests__/resourceId.spec.ts b/packages/crypto/src/__tests__/resourceId.spec.ts
index f92c9ad1..6ccad463 100644
--- a/packages/crypto/src/__tests__/resourceId.spec.ts
+++ b/packages/crypto/src/__tests__/resourceId.spec.ts
@@ -1,10 +1,10 @@
-import { InvalidArgument } from '@tanker/errors';
+import { InternalError, InvalidArgument } from '@tanker/errors';
 import { assert, expect, sinon } from '@tanker/test-utils';
 
 import { random } from '../random';
 import { ready } from '../ready';
-import { getKeyFromCompositeResourceId } from '../resourceId';
-import { MAC_SIZE, SESSION_ID_SIZE } from '../tcrypto';
+import { assertKey, getKeyFromCompositeResourceId } from '../resourceId';
+import { MAC_SIZE, SESSION_ID_SIZE, SYMMETRIC_KEY_SIZE } from '../tcrypto';
 import type { CompositeResourceId } from '../resourceId';
 
 describe('getKeyFromCompositeResourceId', () => {
@@ -36,3 +36,30 @@ describe('getKeyFromCompositeResourceId', () => {
     assert(keyMapper.calledTwice);
   });
 });
+
+describe('assertKey', () => {
+  let resourceId: Uint8Array;
+
+  before(async () => {
+    await ready;
+    resourceId = random(MAC_SIZE);
+  });
+
+  it('succeeds when the key is a Uint8Array', () => {
+    expect(() => assertKey(resourceId, new Uint8Array())).to.not.throw();
+    expect(() => assertKey(resourceId, random(SYMMETRIC_KEY_SIZE))).to.not.throw();
+  });
+
+  it('throws InvalidArgument when the key is null', () => {
+    expect(() => assertKey(resourceId, null)).to.throw(InvalidArgument);
+  });
+
+  it('throws InternalError when the key is falsy but not null', () => {
+    //@ts-expect-error
+    expect(() => assertKey(resourceId, undefined)).to.throw(InternalError);
+    //@ts-expect-error
+    expect(() => assertKey(resourceId, '')).to.throw(InternalError);
+    //@ts-expect-error
+    expect(() => assertKey(resourceId, 0)).to.throw(InternalError);
+  });
+});
diff --git a/packages/crypto/src/resourceId.ts b/packages/crypto/src/resourceId.ts
index 68793976..9569fa34 100644
--- a/packages/crypto/src/resourceId.ts
+++ b/packages/crypto/src/resourceId.ts
@@ -1,4 +1,4 @@
-import { InvalidArgument } from '@tanker/errors';
+import { InternalError, InvalidArgument } from '@tanker/errors';
 import { assertString } from '@tanker/types';
 import type { b64string, Key } from './aliases';
 import type { KeyMapper } from './EncryptionFormats/KeyMapper';
@@ -63,12 +63,17 @@ export const deriveSessionKey = (sessionKey: Key, seed: Uint8Array): Key => gene
 
 export function assertKey(resourceId: Uint8Array, key: Key | null): asserts key is Key {
   if (!key) {
+    if (key !== null) {
+      // This is a safeguard for unexpected behavior between local-storage, network and the resource coalescer:
+      // We suspect that a falsy value different from null is mixed in keys somehow
+      throw new InternalError(`Unreachable code during resource key look-up: ${utils.toBase64(resourceId)}, key found: ${key}`);
+    }
     throw new InvalidArgument(`could not find key for resource: ${utils.toBase64(resourceId)}`);
   }
 }
 
 export const getKeyFromCompositeResourceId = async (resourceId: CompositeResourceId, keyMapper: KeyMapper) => {
-  let key: Key | null;
+  let key: Key | null = null;
   const sessionKey = await keyMapper(resourceId.sessionId);
   if (sessionKey) {
     key = deriveSessionKey(sessionKey, resourceId.resourceId);
@@ -83,7 +88,7 @@ export const getKeyFromCompositeResourceId = async (resourceId: CompositeResourc
 export const getKeyFromResourceId = async (b64resourceId: b64string, keyMapper: KeyMapper) => {
   const resourceId = parseResourceId(b64resourceId);
 
-  let key: Key | null;
+  let key: Key | null = null;
   if ('sessionId' in resourceId) {
     key = await getKeyFromCompositeResourceId(resourceId, keyMapper);
   } else {
diff --git a/packages/datastore/dexie-base/src/index.ts b/packages/datastore/dexie-base/src/index.ts
index 6bcd95af..6435c869 100644
--- a/packages/datastore/dexie-base/src/index.ts
+++ b/packages/datastore/dexie-base/src/index.ts
@@ -308,9 +308,9 @@ export const dexieStoreBase = ((DexieClass: Class<IDexie>): DataStoreAdapter =>
     //   - either withLimit is a Dexie Collection or Table to convert to a Promise<Array<Object>>
     //   - or sortBy() has been called and withLimit is already a Promise<Array<Object>>,
     if (this._isTable(withLimit) || this._isCollection(withLimit)) {
-      res = (withLimit as ITable | ICollection).toArray();
+      res = withLimit.toArray();
     } else {
-      res = withLimit as typeof res;
+      res = withLimit;
     }
 
     return res.then(fromDB);
@@ -323,12 +323,12 @@ export const dexieStoreBase = ((DexieClass: Class<IDexie>): DataStoreAdapter =>
 
   delete = this.withReopen((table: string, id: string) => this._db.table(table).delete(id));
 
-  _isTable(obj: any): boolean {
+  _isTable(obj: any): obj is ITable {
     // @ts-expect-error this._db.Table is a Class (has a prototype)
     return obj instanceof this._db.Table;
   }
 
-  _isCollection(obj: any): boolean {
+  _isCollection(obj: any): obj is ICollection {
     // @ts-expect-error this._db.Collection is a Class (has a prototype)
     return obj instanceof this._db.Collection;
   }
@@ -457,7 +457,7 @@ export const dexieStoreBase = ((DexieClass: Class<IDexie>): DataStoreAdapter =>
       this._isTable(q)
       && (index === sortKey || !index && this.isIndexed(table, sortKey))
     ) {
-      res = (q as ITable).orderBy(sortKey); // ICollection (Dexie)
+      res = q.orderBy(sortKey); // ICollection (Dexie)
     } else {
       res = (q as ICollection).sortBy(sortKey); // Promise<Array<Object>>
     }
@@ -469,9 +469,9 @@ export const dexieStoreBase = ((DexieClass: Class<IDexie>): DataStoreAdapter =>
     let res: ICollection | Promise<Array<Record<string, any>>>;
 
     if (this._isTable(query) || this._isCollection(query)) {
-      res = (query as ITable | ICollection).limit(limit);
+      res = query.limit(limit);
     } else {
-      res = (query as Promise<Array<Record<string, any>>>).then((array) => array.slice(0, limit));
+      res = query.then((array) => array.slice(0, limit));
     }
 
     return res;