Build warnings: mongodb dependencies

[amper43]

We get the following warnings during the build:

WARNING in ./node_modules/require_optional/index.js 97:35-67
Critical dependency: the request of a dependency is an expression
 @ ./node_modules/mongodb/lib/core/index.js
 @ ./node_modules/mongodb/index.js
 @ ./src/services/data_layer/mongodb.ts
 @ ./src/services/data_layer/index.ts
 @ ./src/services/data_service.ts
 @ ./src/migrations.ts
 @ ./src/index.ts
 @ multi babel-polyfill ./src/index.ts

WARNING in ./node_modules/mongodb/lib/operations/connect.js
Module not found: Error: Can't resolve 'mongodb-client-encryption' in '/home/jo/extra/hastic-server/server/node_modules/mongodb/lib/operations'
 @ ./node_modules/mongodb/lib/operations/connect.js
 @ ./node_modules/mongodb/lib/mongo_client.js
 @ ./node_modules/mongodb/index.js
 @ ./src/services/data_layer/mongodb.ts
 @ ./src/services/data_layer/index.ts
 @ ./src/services/data_service.ts
 @ ./src/migrations.ts
 @ ./src/index.ts
 @ multi babel-polyfill ./src/index.ts

WARNING in ./node_modules/mongodb/lib/core/auth/scram.js
Module not found: Error: Can't resolve 'saslprep' in '/home/jo/extra/hastic-server/server/node_modules/mongodb/lib/core/auth'
 @ ./node_modules/mongodb/lib/core/auth/scram.js
 @ ./node_modules/mongodb/lib/core/index.js
 @ ./node_modules/mongodb/index.js
 @ ./src/services/data_layer/mongodb.ts
 @ ./src/services/data_layer/index.ts
 @ ./src/services/data_service.ts
 @ ./src/migrations.ts
 @ ./src/index.ts
 @ multi babel-polyfill ./src/index.ts

we should check whether we need the following dependencies:

• saslprep
• mongodb-client-encryption

and research why we get the following warning:

Critical dependency: the request of a dependency is an expression