test: update test-debugger-low-level to use await/async

PR-URL: #44688
Reviewed-By: Rich Trott <rtrott@gmail.com>

Author: ml7181

test/sequential/test-debugger-low-level.js

@@ -12,28 +12,24 @@ const assert = require('assert');
   const cli = startCLI([fixtures.path('debugger/three-lines.js')]);
   const scriptPattern = /^\* (\d+): \S+debugger(?:\/|\\)three-lines\.js/m;
 
-  function onFatal(error) {
-    cli.quit();
-    throw error;
-  }
-
-  return cli.waitForInitialBreak()
-    .then(() => cli.waitForPrompt())
-    .then(() => cli.command('scripts'))
-    .then(() => {
+  async function testDebuggerLowLevel() {
+    try {
+      await cli.waitForInitialBreak();
+      await cli.waitForPrompt();
+      await cli.command('scripts');
       const [, scriptId] = cli.output.match(scriptPattern);
-      return cli.command(
+      await cli.command(
         `Debugger.getScriptSource({ scriptId: '${scriptId}' })`
       );
-    })
-    .then(() => {
       assert.match(
         cli.output,
         /scriptSource:[ \n]*'(?:\(function \(|let x = 1)/);
       assert.match(
         cli.output,
         /let x = 1;/);
-    })
-    .then(() => cli.quit())
-    .then(null, onFatal);
+    } finally {
+      await cli.quit();
+    }
+  }
+  testDebuggerLowLevel();
 }