LLVM compile fails on WebGL: pinpointing the source

I’m working on a big project which does not seem to build for WebGL in non-development mode.

The error below is printed in the Unity console. According to what I found online, this may be related to some parts of the code not being supported properly by the build pipeline. I found a few examples that went like “you put an empty record in a generic class which was nested in a wibbly-wobbly timey blah blah blah… and that won’t compile”.

Is there a way to find out what part of the C# code is involved in this, or otherwise solve this problem?

Failed running python -E "/home/user/Unity/Hub/Editor/2019.3.9f1/Editor/Data/PlaybackEngines/WebGLSupport/BuildTools/Emscripten/emcc" @"/home/user/ProjectPath/Assets/../Temp/emcc_arguments.resp"

stdout:
stderr:Value:   %542 = landingpad { i8, i32 }          cleanup          catch i8 bitcast ({ i8, i8} @_ZTI22Il2CppExceptionWrapper to i8)LLVM ERROR: Unrecognized struct value

Traceback (most recent call last):  File "/home/user/Unity/Hub/Editor/2019.3.9f1/Editor/Data/PlaybackEngines/WebGLSupport/BuildTools/Emscripten/emcc.py"
line 3063, in     sys.exit(run())  File "/home/user/Unity/Hub/Editor/2019.3.9f1/Editor/Data/PlaybackEngines/WebGLSupport/BuildTools/Emscripten/emcc.py"
(... Python stack trace ...)
line 110, in compile_js    jsrun.timeout_run(subprocess.Popen(backend_args, stdout=subprocess.PIPE, universal_newlines=True), note_args=backend_args)  File "/home/user/Unity/Hub/Editor/2019.3.9f1/Editor/Data/PlaybackEngines/WebGLSupport/BuildTools/Emscripten/tools/jsrun.py"
line 20, in timeout_run    raise Exception('Subprocess "' + ' '.join(note_args) + '" failed with exit code ' + str(proc.returncode) + '!')

Exception: Subprocess "/home/user/Unity/Hub/Editor/2019.3.9f1/Editor/Data/PlaybackEngines/WebGLSupport/BuildTools/Emscripten_FastComp_Linux/llc /tmp/tmplrWw_h/build.bc -march=js -filetype=asm -o /tmp/tmpbbeLPU.4.js -emscripten-stack-size=5242880 -O3 -emscripten-precise-f32 -emscripten-global-base=1024 -emscripten-no-exit-runtime -emscripten-wasm -emscripten-only-wasm" failed with exit code 1!
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr) (at /home/builduser/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:187)

Same problem