Propagate IOException in TagMatcher

This causes a 500 rather than silently omitting a tag from the ref
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Change-Id: I868dd65b285a9b5cd8ce37152d89f086e692f605

java/com/google/gerrit/server/git/TagMatcher.java

@@ -51,13 +51,8 @@ public class TagMatcher {
     this.updated = updated;
   }
 
-  public boolean isReachable(Ref tagRef) {
-    try {
-      tagRef = db.getRefDatabase().peel(tagRef);
-    } catch (IOException e) {
-      // Ignore
-    }
-
+  public boolean isReachable(Ref tagRef) throws IOException {
+    tagRef = db.getRefDatabase().peel(tagRef);
     ObjectId tagObj = tagRef.getPeeledObjectId();
     if (tagObj == null) {
       tagObj = tagRef.getObjectId();

java/com/google/gerrit/server/permissions/DefaultRefFilter.java

@@ -255,8 +255,12 @@ class DefaultRefFilter {
                           .values()
                       : result.values());
       for (Ref tag : deferredTags) {
-        if (tags.isReachable(tag)) {
-          result.put(tag.getName(), tag);
+        try {
+          if (tags.isReachable(tag)) {
+            result.put(tag.getName(), tag);
+          }
+        } catch (IOException e) {
+          throw new PermissionBackendException(e);
         }
       }
     }