fix(cli-repl): account for possibility of process.exit() throwing under coverage MONGOSH-1943 (#2298)

When running under `nyc` for coverage generation, the process's
`process.exit()` internals get monkey-patched to give `nyc` the opportunity
to write coverage data as part of that operation. However, for processes
running under changed working directories, `nyc` may try to write to an incorrect
directory, making the `fs.writeFile()` call fail with an exception,
and so `process.exit()` may not actually stop the process.

This commit adds a `process.abort()` call to make that accounts for this situation,
as well as improved debugging for it.

Author: addaleax

packages/cli-repl/src/run.ts

@@ -232,9 +232,7 @@ async function main() {
         process.env.TEST_USE_STDOUT_FOR_PASSWORD || process.stdout.isTTY
           ? process.stdout
           : process.stderr,
-      // Node.js 20.0.0 made p.exit(undefined) behave as p.exit(0) rather than p.exit()
-      onExit: (code?: number | undefined) =>
-        code === undefined ? process.exit() : process.exit(code),
+      onExit,
       shellHomePaths: shellHomePaths,
       globalConfigPaths: globalConfigPaths,
     });
@@ -341,3 +339,25 @@ function suppressExperimentalWarnings() {
     };
   }
 }
+
+function onExit(code?: number): never {
+  // Node.js 20.0.0 made p.exit(undefined) behave as p.exit(0) rather than p.exit(): (code?: number | undefined): never => {
+  try {
+    try {
+      if (code === undefined) process.exit();
+      else process.exit(code);
+    } finally {
+      if (code === undefined) process.exit();
+      else process.exit(code);
+    }
+  } catch (err) {
+    process.stderr.write(String(err) + '\n');
+  } finally {
+    // Should never be reachable anyway, but nyc monkey-patches process.exit()
+    // internals so that it can always write coverage files as part of the application
+    // shutdown, and that can throw an exception if the filesystem call to write
+    // the coverage file fails.
+    process.stderr.write('process.exit() returned -- aborting\n');
+    process.abort();
+  }
+}