fix: Resolve TypeScript errors

Signed-off-by: Hermes Agent <hermes@nosuchhost>

client/node_modules/abstract-leveldown/test/common.js

@@ -0,0 +1,37 @@
+function testCommon (options) {
+  var factory = options.factory
+  var test = options.test
+
+  if (typeof factory !== 'function') {
+    throw new TypeError('factory must be a function')
+  }
+
+  if (typeof test !== 'function') {
+    throw new TypeError('test must be a function')
+  }
+
+  return {
+    test: test,
+    factory: factory,
+
+    // TODO (next major): remove
+    setUp: options.setUp || noopTest(),
+    tearDown: options.tearDown || noopTest(),
+
+    // TODO (next major): use db.supports instead
+    bufferKeys: options.bufferKeys !== false,
+    createIfMissing: options.createIfMissing !== false,
+    errorIfExists: options.errorIfExists !== false,
+    snapshots: options.snapshots !== false,
+    seek: options.seek !== false,
+    clear: !!options.clear
+  }
+}
+
+function noopTest () {
+  return function (t) {
+    t.end()
+  }
+}
+
+module.exports = testCommon