clean up and rename things to follow proper conventions

src/error-matcher.ts

@@ -0,0 +1,19 @@
+
+export type ErrorMatcher = [number|null, RegExp|null, string];
+
+// exported only for testing purposes
+export const namedMatchersForTesting: { [key: string]: ErrorMatcher } = {
+  /*
+  In due course it may be possible to remove the regex, if/when javascript also exits with code 32.
+   For context see https://github.com/github/semmle-code/pull/36921
+  */
+  noSourceCodeFound: [
+    32,
+    new RegExp("No JavaScript or TypeScript code found\\."),
+    `No source code was seen during the build. Please see...
+https://docs.github.com/en/github/finding-security-vulnerabilities-and-errors-in-your-code/troubleshooting-code-scanning#no-code-found-during-the-build`
+  ],
+};
+
+// we collapse the matches into an array for use in execErrorCatcher
+export const errorMatchers = Object.values(namedMatchersForTesting);