Docker run only works after build - node.js

Question

I can build and run a container with
docker build -t hopperweb:v5-full -f Dockerfile . &&
docker run -p 127.0.0.1:3000:8080 --rm -ti hopperweb:v5-full
However when I run the container I get this error: standard_init_linux.go:211: exec user process caused "exec format error"
docker run -p 127.0.0.1:3000:8080 --rm -ti hopperweb:v5-full
Why is it working when it's run after &&??
I can run the image with bash: docker run -p 127.0.0.1:3000:8080 --rm -ti hopperweb:v5-full bash without issue.
This is my DockerFile
FROM ubuntu:18.04
RUN apt-get update
RUN apt-get install --yes curl
RUN apt-get install --yes sudo ## maybe not necessary, but helpful
RUN apt-get install --yes gnupg
RUN apt-get install --yes git ## not necessary, but helpful
RUN apt-get install --yes vim ## not necessary, but helpful
## INSTALL NPM
RUN curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
RUN echo 'deb https://dl.yarnpkg.com/debian/ stable main' | sudo tee /etc/apt/sources.list.d/yarn.list
RUN apt-get update
RUN apt-get install --yes yarn
RUN apt-get install --yes npm
## COPY IN APP FILES
RUN mkdir /app
COPY hopperweb/ /app/hopperweb/
RUN chmod +x /app/hopperweb/start.sh
RUN /app/hopperweb/start.sh
The contents of start.sh:
#!/bin/bash
cd /app/hopperweb/
yarn start

Answer 1

In your first command, the docker run is never executed, as the last command (start.sh) is run during your build and it will never terminate. So you were still running docker build.
Change the following line
RUN /app/hopperweb/start.sh
to
CMD /app/hopperweb/start.sh
Do not confuse RUN with CMD. RUN actually runs a command and commits the result; CMD does not execute anything at build time, but specifies the intended command for the image.
See: https://docs.docker.com/engine/reference/builder/#cmd