The module that sets source map support does not have its source maps cached/loaded

[Pouja]

Version

24.8.0

Platform

Darwin XXXXX.local 24.6.0 Darwin Kernel Version 24.6.0: Mon Jul 14 11:28:30 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T6030 arm64

Subsystem

module

What steps will reproduce the bug?

Given the following file: enclosing-min.js:

const{setSourceMapsSupport}=require("node:module");setSourceMapsSupport(!0);const functionA=()=>{functionB()};function functionB(){functionC()}const functionC=()=>{functionD()},functionD=()=>{(function(){if(Math.random()>0)throw new Error("an error!")})()},thrower=functionA;try{thrower()}catch(n){throw n}
//# sourceMappingURL=data:application/json;base64,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

Execute with

node enclosing-min.js

How often does it reproduce? Is there a required condition?

Always
No

What is the expected behavior? Why is that the expected behavior?

The error stack trace includes the original lines

What do you see instead?

The stack trace has the minified lines

Additional information

The use case for not using the flag --enable-source-maps is that environment variables are not allowed in AWS Lambda@edge

[Pouja]

My assumption is that the cache at getModuleSourceMapCache() in lib/internal/source_map/source_map_cache.js is only populated with a source map when a cjs module is loaded or an esm module is loaded or eval is executed.

The function prepareStackTraceWithSourceMaps in lib/internal/source_map/prepare_stack_trace.js uses findSource. But findSource only looks at the cache, it will not populate if there is no hit. And because the current module is not loaded, it will return undefined and the original lines are returned. I think.