Server error / 500 when Content-Type not set to application/json

[MonsieurV]

{"compiler":"pdflatex","resources":[{"main":true,"content":"\\documentclass{article}\n\\usepackage{graphicx}\n\\begin{document}\nHello World! \\\\\n\\end{document}"}]}

:authority: latex.ytotech.com
:method: POST
:path: /builds/sync
:scheme: https
accept: */*
accept-encoding: gzip, deflate, br
accept-language: fr-FR,fr;q=0.9,en-US;q=0.8,en;q=0.7
content-length: 167
content-type: text/plain;charset=UTF-8

Jul 16 17:16:54 laura docker-compose[17924]: latex_1  | [ERROR app] Exception on /builds/sync [POST]
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  | Traceback (most recent call last):
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |   File "/root/.local/share/virtualenvs/latex-on-http-zfXpYJxv/lib/python3.7/site-packages/flask/app.py", line 2447, in wsgi_app
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |     response = self.full_dispatch_request()
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |   File "/root/.local/share/virtualenvs/latex-on-http-zfXpYJxv/lib/python3.7/site-packages/flask/app.py", line 1952, in full_dispatch_request
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |     rv = self.handle_user_exception(e)
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |   File "/root/.local/share/virtualenvs/latex-on-http-zfXpYJxv/lib/python3.7/site-packages/flask_cors/extension.py", line 161, in wrapped_function
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |     return cors_after_request(app.make_response(f(*args, **kwargs)))
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |   File "/root/.local/share/virtualenvs/latex-on-http-zfXpYJxv/lib/python3.7/site-packages/flask/app.py", line 1821, in handle_user_exception
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |     reraise(exc_type, exc_value, tb)
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |   File "/root/.local/share/virtualenvs/latex-on-http-zfXpYJxv/lib/python3.7/site-packages/flask/_compat.py", line 39, in reraise
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |     raise value
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |   File "/root/.local/share/virtualenvs/latex-on-http-zfXpYJxv/lib/python3.7/site-packages/flask/app.py", line 1950, in full_dispatch_request
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |     rv = self.dispatch_request()
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |   File "/root/.local/share/virtualenvs/latex-on-http-zfXpYJxv/lib/python3.7/site-packages/flask/app.py", line 1936, in dispatch_request
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |     return self.view_functions[rule.endpoint](**req.view_args)
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |   File "/app/latex-on-http/latexonhttp/api/builds.py", line 98, in compiler_latex
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |     input_spec, error = parse_json_resources_spec(request.get_json())
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |   File "/app/latex-on-http/latexonhttp/resources/json_api.py", line 24, in parse_json_resources_spec
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  |     entry_key for entry_key in json_payload if entry_key in PAYLOAD_KEYS_TO_COPY
Jul 16 17:16:54 laura docker-compose[17924]: latex_1  | TypeError: 'NoneType' object is not iterable