fix: Resolve TypeScript errors

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

client/node_modules/abstract-leveldown/test/open-error-if-exists-test.js

@@ -0,0 +1,37 @@
+exports.setUp = function (test, testCommon) {
+  test('setUp', testCommon.setUp)
+}
+
+exports.errorIfExists = function (test, testCommon) {
+  test('test database open errorIfExists:true', function (t) {
+    var db = testCommon.factory()
+
+    db.open({}, function (err) {
+      t.error(err)
+      db.close(function (err) {
+        t.error(err)
+
+        var async = false
+
+        db.open({ createIfMissing: false, errorIfExists: true }, function (err) {
+          t.ok(err, 'error')
+          t.ok(/exists/.test(err.message), 'error is about already existing')
+          t.ok(async, 'callback is asynchronous')
+          t.end()
+        })
+
+        async = true
+      })
+    })
+  })
+}
+
+exports.tearDown = function (test, testCommon) {
+  test('tearDown', testCommon.tearDown)
+}
+
+exports.all = function (test, testCommon) {
+  exports.setUp(test, testCommon)
+  exports.errorIfExists(test, testCommon)
+  exports.tearDown(test, testCommon)
+}