Docker build for vue project module not found error

Question

I am trying to build a vue app docker image but I keep getting this error

Module not found: Error: Can't resolve './src/main.js' in '/app'

I am using the a multi-stage dockerfile

FROM node:15.4 as build

WORKDIR /app

COPY ./frontend/package.json .

RUN npm install

COPY . .

RUN npm run build


FROM nginx:1.19

COPY ./frontend/nginx/nginx.conf /etc/nginx/nginx.conf

COPY --from=build /app/dist /usr/share/nginx/html

Here's the script section of the package.json file

"scripts": {
    "serve": "vue-cli-service serve",
    "build": "vue-cli-service build",
    "lint": "vue-cli-service lint"
  },

This is a detailed log of the build process

[+] Building 26.9s (14/16)                                                                                                               
 => [internal] load build definition from frontend.dockerfile                                                                       0.0s
 => => transferring dockerfile: 293B                                                                                                0.0s
 => [internal] load .dockerignore                                                                                                   0.0s
 => => transferring context: 34B                                                                                                    0.0s
 => [internal] load metadata for docker.io/library/nginx:1.19                                                                       2.5s
 => [internal] load metadata for docker.io/library/node:15.4                                                                        2.4s
 => [auth] library/node:pull token for registry-1.docker.io                                                                         0.0s
 => [auth] library/nginx:pull token for registry-1.docker.io                                                                        0.0s
 => [build 1/6] FROM docker.io/library/node:15.4@sha256:a76eb778d162f8fd96138d9ca7dbd14b8916c201775a97d2f2aa22e9f13eb105            0.0s
 => [stage-1 1/3] FROM docker.io/library/nginx:1.19@sha256:df13abe416e37eb3db4722840dd479b00ba193ac6606e7902331dcea50f4f1f2         0.0s
 => [internal] load build context                                                                                                   8.5s
 => => transferring context: 166.03MB                                                                                               8.4s
 => CACHED [build 2/6] WORKDIR /app                                                                                                 0.0s
 => CACHED [build 3/6] COPY ./frontend/package.json .                                                                               0.0s
 => CACHED [build 4/6] RUN npm install                                                                                              0.0s
 => [build 5/6] COPY . .                                                                                                            7.4s
 => ERROR [build 6/6] RUN npm run build                                                                                             8.3s
------                                                                                                                                   
 > [build 6/6] RUN npm run build:                                                                                                        
#14 2.913 
#14 2.913 > [email protected] build
#14 2.913 > vue-cli-service build
#14 2.913 
#14 4.668 All browser targets in the browserslist configuration have supported ES module.

I move the frontend folder from the project to stand alone and I am able to build the image and run a container based on it successfully.

What could possibly be wrong here?