wrap plugin indexer in try/catch block (#3812)

diff --git a/kythe/typescript/indexer.ts b/kythe/typescript/indexer.ts
index b76857c..50fd4ac 100644
--- a/kythe/typescript/indexer.ts
+++ b/kythe/typescript/indexer.ts
@@ -1216,9 +1216,13 @@
 
   if (plugins) {
     for (const plugin of plugins) {
-      plugin.index(
-          (path: string) => getFileVName(path, pathVNames, vname), paths,
-          program, emit);
+      try {
+        plugin.index(
+            (path: string) => getFileVName(path, pathVNames, vname), paths,
+            program, emit);
+      } catch (err) {
+        console.error(`Plugin ${plugin.name} errored: ${err}`);
+      }
     }
   }
 }