VSCode Debugging in Docker: Unable to resolve non-existing file

I am programming in c++ using docker. Recently I tried to set up my GDB debugger in VSCode to help with some issues I was having and it turns out that was a bigger pain to do than I thought. I've gotten close but I keep getting the error Error: Unable to resolve non-existing file '/mnt/files/p5-student/src/main.cpp'. I'm not sure why this is happening.

I followed most of the instructions from this post, but I skipped a decent amount of steps because I don't want to create a new docker image, I just want to use one provided by my professor.

This is my launch.json:

{
    "version": "0.2.0",
    "configurations": [{
        "name": "(gdb) Pipe Launch",
        "type": "cppdbg",
        "request": "launch",
        "program": "/mnt/files/p5-student/main",
        "cwd": "/mnt/files/p5-student",
        "args": [],
        "stopAtEntry": true,
        "environment": [],
        "externalConsole": true,
        "pipeTransport": {
            "debuggerPath": "/usr/bin/gdb",
            "pipeProgram": "docker",
            "pipeArgs": ["exec", "-i", "os_container", "sh", "-c"],
            "pipeCwd": "${workspaceRoot}"
        },
        "MIMode": "gdb",
        "setupCommands": [{
            "description": "Enable pretty-printing for gdb",
            "text": "-enable-pretty-printing",
            "ignoreFailures": true
        }]
    }, ]
}

My code is stored in my docker container in /mnt/files/p5-student and our MakeFile creates an executable called main

This is tasks.json

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "prepare to debug",
            "type": "shell",
            "command": "docker start -i os_container",
            "group": "build",
            "problemMatcher": []
        }
    ]
}

I have an already created docker container, so I just want to start it with this task.

When I run the debugger I get the first local variable from main.cpp, but then VSCode hits me with Error: Unable to resolve non-existing file '/mnt/files/p5-student/src/main.cpp'