code: function fixAcornEsmImport() {
  	return {
  		name: 'fix-acorn-esm-import',
  		renderChunk(code, chunk, options) {
  			if (/esm?/.test(options.format)) {
  				let found = false;
  				const fixedCode = code.replace(expectedAcornImport, () => {
  					found = true;
  					return newAcornImport;
  				});
  				if (!found) {
  					this.error(
  						'Could not find expected acorn import, please deactive this plugin and examine generated code.'
  					);
  				}
  				return fixedCode;
  			}
  		}
  	};
  }
docs: by default, rollup-plugin-commonjs will translate require statements as default imports which can cause issues for secondary tools that use the ESM version of acorn