Don't npm install the parent project with no args

Author: jablko

src/testRunner/externalCompileRunner.ts

@@ -75,7 +75,7 @@ abstract class ExternalCompileRunnerBase extends RunnerBase {
                     exec("npm", ["i", "--ignore-scripts"], { cwd, timeout: timeout / 2 }); // NPM shouldn't take the entire timeout - if it takes a long time, it should be terminated and we should log the failure
                 }
                 const args = [path.join(Harness.IO.getWorkspaceRoot(), "built/local/tsc.js")];
-                if (types) {
+                if (types?.length) {
                     args.push("--types", types.join(","));
                     // Also actually install those types (for, eg, the js projects which need node)
                     exec("npm", ["i", ...types.map(t => `@types/${t}`), "--no-save", "--ignore-scripts"], { cwd: originalCwd, timeout: timeout / 2 }); // NPM shouldn't take the entire timeout - if it takes a long time, it should be terminated and we should log the failure