Fix error messages text when validating compilerOptions.

PiperOrigin-RevId: 230998217
diff --git a/internal/tsc_wrapped/compiler_host.ts b/internal/tsc_wrapped/compiler_host.ts
index 96eb3d2..04c35fd 100644
--- a/internal/tsc_wrapped/compiler_host.ts
+++ b/internal/tsc_wrapped/compiler_host.ts
@@ -29,10 +29,10 @@
     throw new Error(`compilerOptions.rootDirs should be set by tsconfig.bzl`);
   }
   if (!options.rootDir) {
-    throw new Error(`compilerOptions.rootDirs should be set by tsconfig.bzl`);
+    throw new Error(`compilerOptions.rootDir should be set by tsconfig.bzl`);
   }
   if (!options.outDir) {
-    throw new Error(`compilerOptions.rootDirs should be set by tsconfig.bzl`);
+    throw new Error(`compilerOptions.outDir should be set by tsconfig.bzl`);
   }
   return options as BazelTsOptions;
 }