TypeError: Cannot read property 'concat' of null

I keep getting the following error in my nodejs application. I am using node v8.11.1 and grpc v1.11.3. The same code was working fine a few days ago.

    TypeError: Cannot read property 'concat' of null
        at Object.getInterceptingCall (/home/dipu/projects/tee/node_modules/grpc/src/client_interceptors.js:1376:39)
        at ServiceClient.Client.makeUnaryRequest (/home/dipu/projects/tee/node_modules/grpc/src/client.js:471:47)
        at apply (/home/dipu/projects/tee/node_modules/lodash/lodash.js:478:17)
        at ServiceClient.wrapper (/home/dipu/projects/tee/node_modules/lodash/lodash.js:5337:16)
        at Promise (/home/dipu/projects/tee/node_modules/grpc-promisify/src/index.js:22:26)
        at new Promise (<anonymous>)
        at ServiceClient.client.(anonymous function) [as getTeeFeed] (/home/dipu/projects/tee/node_modules/grpc-promisify/src/index.js:21:14)
        at Object.shadowClient.(anonymous function) [as getTeeFeed] (/home/dipu/projects/tee/build/webpack:/server/helper/grpc-client.js:40:27)
        at /home/dipu/projects/tee/build/webpack:/server/api/contents.js:31:33
        at Layer.handle [as handle_request] (/home/dipu/projects/tee/node_modules/express/lib/router/layer.js:95:5)
        at next (/home/dipu/projects/tee/node_modules/express/lib/router/route.js:137:13)
        at Route.dispatch (/home/dipu/projects/tee/node_modules/express/lib/router/route.js:112:3)
        at Layer.handle [as handle_request] (/home/dipu/projects/tee/node_modules/express/lib/router/layer.js:95:5)
        at /home/dipu/projects/tee/node_modules/express/lib/router/index.js:281:22
        at Function.process_params (/home/dipu/projects/tee/node_modules/express/lib/router/index.js:335:12)
        at next (/home/dipu/projects/tee/node_modules/express/lib/router/index.js:275:10)

EDIT: I updated from grpc v1.7.3. After I reverted back to old package-lock.json the error was fixed. But still a question remains: why this error happened?

[drobertduke]

@murgatroid99 The client constructor ensures that client[functionName].interceptors is an array, which ensures all those other calls return arrays https://github.com/grpc/grpc-node/blob/master/packages/grpc-native-core/src/client.js#L391

@dipu-bd You are using a grpc-promisify library which clobbers the client[functionName] function, removing the interceptors attribute https://github.com/leaves4j/grpc-promisify/blob/master/src/index.js#L14

I can update the signatures of the private methods to only return arrays but the immediate fix here is to not clobber client[functionName], and if you do, reattach .interceptors.

[murgatroid99]

The grpc package has been deprecated. We recommend using @grpc/grpc-js instead. That library has a different interceptor implementation, which shouldn’t have these issues.