fix: Crashes due to shadowed global scope object

[zermelo-wisen]

Fixes #159.

Summary

This pull request addresses an essential issue by changing instrumentation to prevent potential crashes in environments where global or globalThis objects are shadowed or manipulated. These updates ensure the stability and reliability of the AppMap recording functionality.

Original Code Example

function testFun(arg) {
 return arg + 1;
}

Transformation Before This Fix

function testFun(arg) {
  return global.AppMapRecodHook.call(this, () => {
    return arg + 1;
  }, arguments, __appmapFunctionRegistry[0]);
}

Transformation After This Fix

// These are added to the top of the module/script

function __appmapRecordInit() {
 let g = null;
 try {
   g = global.AppMapRecordHook;
 } catch (e) {
   try {
     g = globalThis.AppMapRecordHook;
   } catch (e) {}
   // If global/globalThis is shadowed in the top level, we'll get:
   // ReferenceError: Cannot access 'global' before initialization.   
 }
 // Bypass recording if we can't access recorder to prevent a crash.
 return g ?? ((fun, argsArg) => fun.apply(this, argsArg));
}

const __appmapRecord = __appmapRecordInit();

// Not calling global.AppMapRecordHook directly in the function
// prevents shadowing error in the function and pushes the check
// to a single place where it is run just once in the module/script
// initialization.

function testFun(arg) {
  return __appmapRecord.call(this, () => {
    return arg + 1;
  }, arguments, __appmapFunctionRegistry[0]);
}

[dividedmind]

Great work! Thanks.

[appland-release]

🎉 This PR is included in version 2.24.2 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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