Node max_old_space_size causes build to fail immediately - node.js

Question

I am trying to build Mattermost on an armv7a host, but Node is running out of memory during the webpack build. The solution for this seems to be supposed to set max_old_space_size in NODE_OPTIONS, but counterintuitively doing this seems to cause the build to fail immediately the first time node is run.
The host has 2G of RAM, but I have added 12G of swap to no effect.
CPU: Marvell Armada 370/XP (Device Tree) (4) # 1.333GHz
Node: v13.13.0
Crash when building normally, this occurs after about 30 minutes:
Building mattermost Webapp
rm -rf dist
npm run build
> mattermost-webapp#0.0.1 build /var/tmp/portage/www-apps/mattermost-server-5.22.0/work/mattermost-server-5.22.0/src/github.com/mattermost/mattermost-server/client
> cross-env NODE_ENV=production webpack --display-error-details --verbose
<--- Last few GCs --->
[17346:0x1e80ee8] 2121678 ms: Mark-sweep 501.2 (506.3) -> 500.7 (506.3) MB, 1640.3 / 0.0 ms (average mu = 0.108, current mu = 0.029) allocation failure scavenge might not succeed
[17346:0x1e80ee8] 2123903 ms: Mark-sweep 501.2 (506.3) -> 500.8 (506.3) MB, 2178.0 / 0.0 ms (average mu = 0.064, current mu = 0.021) allocation failure scavenge might not succeed
<--- JS stacktrace --->
==== JS stack trace =========================================
0: ExitFrame [pc: 0x1468e00]
1: StubFrame [pc: 0x14098a4]
Security context: 0x31940491 <JSObject>
2: /* anonymous */(aka /* anonymous */) [0x9e4bbf89] [/var/tmp/portage/www-apps/mattermost-server-5.22.0/work/mattermost-server-5.22.0/src/github.com/mattermost/mattermost-server/client/node_modules/webpack-sources/l
ib/applySourceMap.js:~58] [pc=0x9c9a9b44](this=0x40f0027d <undefined>,0x4c40d721 <String[2]: e}>,0xa5f1ebcd <Object ...
FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! mattermost-webapp#0.0.1 build: `cross-env NODE_ENV=production webpack --display-error-details --verbose`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the mattermost-webapp#0.0.1 build script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
Crash when adding NODE_OPTIONS=max_old_space_size=4196 (occurs immediately):
make -j4 build
Getting dependencies using npm
npm install
<--- Last few GCs --->
[35:0x1ea1e00] 394 ms: Mark-sweep 1.0 (2.5) -> 0.9 (3.5) MB, 10.7 / 0.0 ms (average mu = 0.724, current mu = 0.096) allocation failure GC in old space requested
[35:0x1ea1e00] 401 ms: Mark-sweep 0.9 (3.5) -> 0.9 (2.0) MB, 6.6 / 0.0 ms (average mu = 0.627, current mu = 0.063) last resort GC in old space requested
[35:0x1ea1e00] 409 ms: Mark-sweep 0.9 (2.0) -> 0.9 (2.0) MB, 8.6 / 0.0 ms (average mu = 0.463, current mu = 0.005) last resort GC in old space requested
<--- JS stacktrace --->
==== JS stack trace =========================================
0: ExitFrame [pc: 0x1489e00]
Security context: 0x375c0491 <JSObject>
1: test [0x375c4d6d](this=0x5cfb2121 <JSRegExp <String[#14]: (?:^|\/)\.?\.$>>,0x33167c71 <String[#27]: ../lib/utils/unsupported.js>)
2: /* anonymous */(aka /* anonymous */) [0x375ca1a5] [internal/per_context/primordials.js:23] [bytecode=0x375f6695 offset=28](this=0x4938027d <undefined>,0x5cfb2121 <JSRegExp <String[#14]: (?:^|\/)\.?\.$>>)
3: arguments adap...
FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - JavaScript heap out of memory
make: *** [Makefile:36: node_modules] Aborted
Why does changing max_old_space_size cause Node to run out of memory immediately?
Edit: some more information to add...I have been using https://github.com/Data-Wrangling-with-JavaScript/nodejs-memory-test as a minimal test case to demonstrate. It would seem that Node is refusing to consider swap space as usable memory. For example, if I run:
$ node nodejs-memory-test/index.js
It allocates up to the last line:
Allocated since start 0.49 GB
before crashing. If I run:
$ NODE_OPTIONS="--max-old-space-size=1024" node nodejs-memory-test/index.js
it successfully runs up to
Allocated since start 0.98 GB
before crashing.
However, if I run:
NODE_OPTIONS="--max-old-space-size=8196" node nodejs-memory-test/index.js
it only gets through a handful of lines before dying on
Allocated since start 0.01 GB
Can somebody help me understand what is going on?