Frequently hitting 'unreachable' errors with many source maps in memory

Start in lib/source-map-consumer.js around BasicSourceMapConsumer._parseMappings, _getMappingsPtr, and originalPositionFor, then inspect lib/wasm.js and the reported WebAssembly failure path. Reproduce the workload with many SourceMapConsumers and confirm whether allocation failure causes the unreachable error. Done means callers can distinguish this memory condition and recover by dropping cached data.

I'm operating a service which sourcemaps JavaScript Self-Profiling data from production. We have several versions of our app running concurrently, with different source maps. The service keeps an LRU cache of SourceMapConsumers with a size limit roughly calculated from smc._mappings.length. This lets us keep around 100 SourceMapConsumers active at a time before running into the WebAssembly memory limit.

However, we often see unreachable errors like the following:

RuntimeError: unreachable
     at wasm://wasm/0002f63a:wasm-function[54]:0xb65c
     at wasm://wasm/0002f63a:wasm-function[22]:0x9647
     at BasicSourceMapConsumer._parseMappings (/work/node_modules/source-map/lib/source-map-consumer.js:306:47)
     at BasicSourceMapConsumer._getMappingsPtr (/work/node_modules/source-map/lib/source-map-consumer.js:289:12)
     at /work/node_modules/source-map/lib/source-map-consumer.js:500:16
     at Object.withMappingCallback (/work/node_modules/source-map/lib/wasm.js:125:13)
     at BasicSourceMapConsumer.originalPositionFor (/work/node_modules/source-map/lib/source-map-consumer.js:496:16)
     at file:///work/dist/mapTrace.js:44:34
     at file:///work/dist/mapTrace.js:53:11
     at Array.map (<anonymous>)

I believe this indicates an out-of-memory error, where source-map's rust code tries to allocate something but can't.

Could it be possible to gracefully recover from this? I believe Rust doesn't really support graceful recovery from OOM, but perhaps source-map could check whether there's enough memory available to allocate for a SourceMapConsumer before allocating, and throw some other kind of error? That would allow using that signal to drop some old data from our cache.