Actions: dont fail if no JS/TS code was found

Author: asgerf

javascript/extractor/src/com/semmle/js/extractor/AutoBuild.java

@@ -489,13 +489,15 @@ public int run() throws IOException {
         diagnosticsToClose.forEach(DiagnosticWriter::close);
       }
 
-      if (!hasSeenCode()) {
+      // Fail extraction is no relevant files were found.
+      if (!seenFiles || !hasSeenCode() && !EnvironmentVariables.isActionsExtractor()) {
         if (seenFiles) {
           warn("Only found JavaScript or TypeScript files that were empty or contained syntax errors.");
         } else {
           warn("No JavaScript or TypeScript code found.");
         }
-        // ensuring that the finalize steps detects that no code was seen.
+        // Ensuring that the finalize steps detects that no code was seen.
+        // This is necessary to ensure we don't produce an overlay-base database without externs.
         Path srcFolder = Paths.get(EnvironmentVariables.getWipDatabase(), "src");
         try {
           FileUtil8.recursiveDelete(srcFolder);

javascript/extractor/src/com/semmle/js/extractor/EnvironmentVariables.java

@@ -18,6 +18,9 @@ public class EnvironmentVariables {
   public static final String CODEQL_EXTRACTOR_JAVASCRIPT_WIP_DATABASE_ENV_VAR =
       "CODEQL_EXTRACTOR_JAVASCRIPT_WIP_DATABASE";
 
+  public static final String CODEQL_EXTRACTOR_ACTIONS_WIP_DATABASE_ENV_VAR =
+      "CODEQL_EXTRACTOR_ACTIONS_WIP_DATABASE";
+
   public static final String CODEQL_DIST_ENV_VAR = "CODEQL_DIST";
 
   /**
@@ -94,4 +97,8 @@ public static String getCodeQLDist() {
   public static String getWipDatabase() {
     return Env.systemEnv().getNonEmpty(CODEQL_EXTRACTOR_JAVASCRIPT_WIP_DATABASE_ENV_VAR);
   }
+
+  public static boolean isActionsExtractor() {
+    return Env.systemEnv().getNonEmpty(CODEQL_EXTRACTOR_ACTIONS_WIP_DATABASE_ENV_VAR) != null;
+  }
 }