Running "ng build" in docker container gives "project definition could not be found"

I'm trying to build an Angular + Spring-boot project using Maven and deploy it as a docker container. To compile the application I run

mvn package

which at some point runs ng build. It works as intended when I do it on my local machine. But when I copy files into a docker image and try to run mvn package, I get an error

[INFO] --- frontend-maven-plugin:1.11.2:npm (npm-build) @ tradingSandbox ---
[INFO] Running 'npm run-script build' in /
[INFO] 
[INFO] > trading-sandbox@0.0.0 build /
[INFO] > ng build
[INFO] 
[INFO] The build command requires to be run in an Angular project, but a project definition could not be found.
[INFO] npm ERR! code ELIFECYCLE
[INFO] npm ERR! errno 1
[INFO] npm ERR! trading-sandbox@0.0.0 build: `ng build`
[INFO] npm ERR! Exit status 1
[INFO] npm ERR! 
[INFO] npm ERR! Failed at the trading-sandbox@0.0.0 build script.
[INFO] npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
[INFO] 
[INFO] npm ERR! A complete log of this run can be found in:
[INFO] npm ERR!     /root/.npm/_logs/2021-02-23T09_15_24_641Z-debug.log
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------

The root directory contains proper angular.json file and Maven downloads correct version of nodejs. Because it is inside a docker image, I am unable to access debug.log. Needless to say I am unexperienced with using a Docker.

Dockerfile

FROM maven:3.6.3-jdk-11

COPY . /

RUN cd /
RUN ls -a

ENV PORT=8080

RUN mvn package

CMD mvn spring-boot:run -Dspring-boot.run.profiles=$PROFILE -Dserver.port=$PORT

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>tradingSandbox</artifactId>
    <version>0.0.1</version>
    <name>tradingSandbox</name>
    <description>Trading sandbox</description>
    <properties>
        <java.version>11</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-security</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <!--    Database controller for deployment  -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

<!--    Database controller for testing -->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.security</groupId>
            <artifactId>spring-security-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt-api</artifactId>
            <version>0.10.7</version>
        </dependency>

        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt-impl</artifactId>
            <version>0.10.7</version>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt-jackson</artifactId>
            <version>0.10.7</version>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
    <resources>
      <resource>
        <directory>src/main/resources</directory>
        <filtering>true</filtering>
      </resource>
    </resources>

        <plugins>

            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

            <plugin>
        <groupId>com.github.eirslett</groupId>
        <artifactId>frontend-maven-plugin</artifactId>
        <version>1.11.2</version>
                <configuration>
                    <nodeVersion>v12.18.4</nodeVersion>
                </configuration>
                <executions>

                    <execution>
                        <id>install-npm</id>
                        <goals>
                            <goal>install-node-and-npm</goal>
                        </goals>
                    </execution>

                    <execution>
                        <id>npm-install</id>
                        <goals>
                            <goal>npm</goal>
                        </goals>
                    </execution>

          <execution>
            <id>npm-build</id>
            <goals>
              <goal>npm</goal>
            </goals>
            <configuration>
              <arguments>run-script build</arguments>
            </configuration>
          </execution>

                </executions>
            </plugin>

        </plugins>
    </build>

</project>