fix: skip snap test directories without steps.json

Print a warning and skip test case directories that are missing
steps.json instead of crashing with ENOENT.

Author: fengmk2

packages/cli/snap-tests/fmt-check-ignore-temp-config/snap.txt

@@ -1,7 +1,6 @@
 [1]> vp fmt --check # Test that vp fmt --check ignores the temp config file
 Checking formatting...
 src/valid.js (<variable>ms)
-steps.json (<variable>ms)
 
-Format issues found in above 2 files. Run without `--check` to fix.
+Format issues found in above 1 files. Run without `--check` to fix.
 Finished in <variable>ms on 4 files using <variable> threads.

packages/tools/src/snap-test.ts

@@ -130,6 +130,10 @@ export async function snapTest() {
     if (caseName.startsWith('.')) {
       continue;
     } // Skip hidden files like .DS_Store
+    if (!fs.existsSync(path.join(casesDir, caseName, 'steps.json'))) {
+      console.warn('Warning: %s has no steps.json, skipping', caseName);
+      continue;
+    }
     if (caseName.includes(filter)) {
       taskFunctions.push(() => runTestCase(caseName, tempTmpDir, casesDir, values['bin-dir']));
     }