Avoid using source-map-support/register

This was highly unperformant.

lib/assertions.ts

@@ -9,7 +9,7 @@ export function fail(message: string) {
 }
 
 export function assert(value: unknown, message: string): asserts value {
-  if (value) {
+  if (value != null) {
     return;
   }
 

lib/diagnostics/diagnose.ts

@@ -1,4 +1,3 @@
-import "source-map-support/register";
 import fs from "fs/promises";
 import path from "path";
 import util from "util";
@@ -14,6 +13,7 @@ import {
 import { generateMessages } from "@cucumber/gherkin";
 import { IdGenerator, SourceMediaType } from "@cucumber/messages";
 import * as esbuild from "esbuild";
+import sourceMap from "source-map";
 import { assert, assertAndReturn } from "../assertions";
 import { createAstIdMap } from "../ast-helpers";
 import { ensureIsRelative } from "../helpers/paths";
@@ -138,7 +138,7 @@ export async function diagnose(configuration: {
       const esbuildResult = await esbuild.build({
         entryPoints: [inputFileName],
         bundle: true,
-        sourcemap: true,
+        sourcemap: "external",
         outfile: outputFileName,
       });
 
@@ -175,6 +175,33 @@ export async function diagnose(configuration: {
       await fs.rm(outputFileName).catch(() => true);
     }
 
+    const consumer = await new sourceMap.SourceMapConsumer(
+      (await fs.readFile(outputFileName + ".map")).toString()
+    );
+
+    for (const stepDefinition of registry.stepDefinitions) {
+      const originalPosition = position(stepDefinition);
+
+      const newPosition = consumer.originalPositionFor(originalPosition);
+
+      stepDefinition.position = {
+        line: assertAndReturn(
+          newPosition.line,
+          "Expected to find a line number"
+        ),
+        column: assertAndReturn(
+          newPosition.column,
+          "Expected to find a column number"
+        ),
+        source: assertAndReturn(
+          newPosition.source,
+          "Expected to find a source"
+        ),
+      };
+    }
+
+    consumer.destroy();
+
     const options = {
       includeSource: false,
       includeGherkinDocument: true,

package.json

@@ -66,7 +66,7 @@
     "module-alias": "^2.2.2",
     "node-hook": "^1.0.0",
     "resolve-pkg": "^2.0.0",
-    "source-map-support": "^0.5.21",
+    "source-map": "^0.7.4",
     "uuid": "^8.3.2"
   },
   "devDependencies": {