Silently ignore missing keys

A recent change in HH\facts_parse() made it no longer return empty vecs
for entities kinds that are not declared in the file.
So files without constants do not return `"constants" => vec[]` anymore.
Supply a default value of `vec[]` to match the old behavior and fix CI.

bin/hh-autoload.hack

@@ -69,16 +69,16 @@ final class GenerateScript {
         continue;
       }
       $file_facts = $file_facts as dynamic;
-      foreach ($file_facts['types'] as $type) {
+      foreach ($file_facts['types'] ?? vec[] as $type) {
         $map['class'][\strtolower($type['name'] as string)] = $path;
       }
-      foreach ($file_facts['constants'] as $const) {
+      foreach ($file_facts['constants'] ?? vec[] as $const) {
         $map['constant'][$const as string] = $path;
       }
-      foreach ($file_facts['functions'] as $fun) {
+      foreach ($file_facts['functions'] ?? vec[] as $fun) {
         $map['function'][\strtolower($fun as string)] = $path;
       }
-      foreach ($file_facts['typeAliases'] as $type) {
+      foreach ($file_facts['typeAliases'] ?? vec[] as $type) {
         $map['type'][\strtolower($type as string)] = $path;
       }
     }
@@ -152,8 +152,8 @@ final class GenerateScript {
       ? $config['devFailureHandler']
       : $config['failureHandler'];
 
-    $emit_facts_forwarder_file = $config['useFactsIfAvailable'] &&
-      !$options['no-facts'];
+    $emit_facts_forwarder_file =
+      $config['useFactsIfAvailable'] && !$options['no-facts'];
 
     (new Writer())
       ->setBuilder($importer)

src/TypeAssert.hack

@@ -86,7 +86,7 @@ function is_array_of_shapes_with_name_field(
   mixed $value,
   string $field,
 ): varray<shape('name' => string)> {
-  $msg = $field.'should be an array<shape(\'name\' => string)>';
+  $msg = $field.'should be an vec<shape(\'name\' => string)>';
   invariant($value is Traversable<_>, '%s', $msg);
   $out = varray[];
   foreach ($value as $it) {

src/builders/FactParseScanner.hack

@@ -40,19 +40,19 @@ final class FactParseScanner implements Builder {
       try {
         $out[$file] = shape(
           'types' => TypeAssert\is_array_of_shapes_with_name_field(
-            $facts['types'] ?? null,
+            $facts['types'] ?? vec[],
             'FactParse types',
           ),
           'constants' => TypeAssert\is_array_of_strings(
-            $facts['constants'] ?? null,
+            $facts['constants'] ?? vec[],
             'FactParse constants',
           ),
           'functions' => TypeAssert\is_array_of_strings(
-            $facts['functions'] ?? null,
+            $facts['functions'] ?? vec[],
             'FactParse functions',
           ),
           'typeAliases' => TypeAssert\is_array_of_strings(
-            $facts['typeAliases'] ?? null,
+            $facts['typeAliases'] ?? vec[],
             'FactParse typeAliases',
           ),
         );