Better way to run python & display python errors from PHP - php

Question

I am running a webserver for my laboratory that basically has a bunch of scripts I wrote in python for processing and analyzing tabular data.
I have a DigitalOcean droplet with a Laravel application deployed on it. When I want to run a script, I have the user upload some data file, and then from the PHP controller run:
shell_exec(python my_script.py arg1 arg2 etc);
The problem is, there are differences in dependencies and libraries between my development environment and 'production' environment. As such, when I try to run the script from the webserver and there is a python error, the object returned by shell_exec is just null. When the PHP blade template tries to parse/get data from this object, I get an error like so:
In this case, 'matchCount' is just a variable stored within a python list like this:
#Label peptides we found experimentally but do not have an in silico match for... as to predict contaminants
output = {
'sequence': protSeq,
'peptides': pepList,
'observablePeptideCount': str(len(pepList)),
'possibleObserved': possibleObserved,
'matchCount': matchCount,
'coverage': matchSumAA/protSeqAALength*100,
'massList': massList,
'tolerances': tolerances,
}
output = json.dumps(output)
The problem is, I understand the python script failed somewhere, but the error log does not give any indication of why or where. Is there some way I can have the webpage output the python error so I can correct it in the production environment?
Is there a better way to be doing all of this? Thank you for any help.

Answer 1

I won't recommend you print things out in production, but if it's a last resort you can try this:
<?php
$output = '';
$result = '';
exec('python my_script.py arg1 arg2 etc 2>&1', $output, $result);
var_dump($output); // all the output is here
var_dump($result); // gives an exit code, might be 1 if it's error