@fastly/js-compute/dist/compiler-steps/addFastlyHelpers.js

JavaScript SDK and CLI for building JavaScript applications on [Fastly Compute](https://www.fastly.com/products/edge-compute/serverless).

// Compiler Step - Add Fastly Helpers
// This step usually runs last before composing sourcemaps.
export const addFastlyHelpersStep = {
    outFilename: '__fastly_helpers.js',
    async fn(ctx, index) {
        await ctx.magicStringWriter(this.outFilename, async (magicString) => {
            // MISC HEADER
            const SOURCE_FILE_NAME = 'fastly:app.js';
            const STACK_MAPPING_HEADER = `\
//# sourceURL=${SOURCE_FILE_NAME}
globalThis.__FASTLY_GEN_FILE = "${SOURCE_FILE_NAME}";
globalThis.__orig_console_error = console.error.bind(console);
globalThis.__fastlyMapAndLogError = (e) => {
  for (const line of globalThis.__fastlyMapError(e)) {
    globalThis.__orig_console_error(line);
  }
};
globalThis.__fastlyMapError = (e) => {
  return [
    '(Raw error) - build with --enable-stack-traces for mapped stack information.',
    e,
  ];   
};
`;
            magicString.prepend(STACK_MAPPING_HEADER);
        });
        await ctx.maybeWriteDebugIntermediateFiles(`__${index + 1}_fastly_helpers.js`);
    },
};