The runtime build installs the module's SDK itself and shows its compiler's output

A module never built on this workstation had no node_modules, tsc failed on the
first import behind /dev/null, and the suite reported a build that said nothing.

src/rebuild.ts

@@ -134,7 +134,7 @@ export function rebuild(env: NodeJS.ProcessEnv = process.env, testFiles: string[
       // the code in front of you, which is the whole of 005.
       throw new Error(
         `could not build the ${build.what}: ${build.argv.join(" ")} in ${build.in}\n\n` +
-          `${(ran.stderr || ran.stdout || String(ran.error)).trim()}`,
+          `${(ran.stderr || ran.stdout || (ran.error ? String(ran.error) : `exit status ${ran.status}, and it said nothing`)).trim()}`,
       );
     }
     built.push(build.what);