Throw error early rather than warning

src/init-action.ts

@@ -389,6 +389,15 @@ async function run(startedAt: Date) {
       logger,
     });
 
+    if (
+      config.languages.includes(KnownLanguage.swift) &&
+      process.platform === "linux"
+    ) {
+      throw new ConfigurationError(
+        `Swift analysis on Ubuntu runner images is no longer supported. Please migrate to a macOS runner.`,
+      );
+    }
+
     if (repositoryPropertiesResult.isFailure()) {
       addNoLanguageDiagnostic(
         config,
@@ -499,15 +508,6 @@ async function run(startedAt: Date) {
       );
     }
 
-    if (
-      config.languages.includes(KnownLanguage.swift) &&
-      process.platform === "linux"
-    ) {
-      logger.warning(
-        `Swift analysis on Ubuntu runner images is no longer supported. Please migrate to a macOS runner if this affects you.`,
-      );
-    }
-
     if (
       config.languages.includes(KnownLanguage.go) &&
       process.platform === "linux"