catch backend errors in 'get' or 'getOrElse' and follow 'orElse' when they occur

lib/cache.js

@@ -137,7 +137,7 @@ void function () {
       }).nodeify(cb);
     };
     Cache.prototype.getOrElse = function (rawKey, val, opts, cb) {
-      var cache$, key, refreshValue, verifyFreshness;
+      var cache$, handleError, key, refreshValue, verifyFreshness;
       key = this.applyPrefix(rawKey);
       cache$ = optionalOpts(opts, cb);
       cb = cache$.cb;
@@ -169,7 +169,10 @@ void function () {
           return null != (null != wrappedValue ? wrappedValue.d : void 0) ? null != wrappedValue ? wrappedValue.d : void 0 : this$.staleOrPending[key];
         };
       }(this);
-      return this.getWrapped(key).then(verifyFreshness).nodeify(cb);
+      handleError = function (error) {
+        return null;
+      };
+      return this.getWrapped(key)['catch'](handleError).then(verifyFreshness).nodeify(cb);
     };
     return Cache;
   }();

package.json

@@ -32,6 +32,7 @@
     "memcached": "~0.2.0"
   },
   "devDependencies": {
+    "bondjs": "~1.0.0",
     "coffee-script-redux": "2.0.0-beta7",
     "expect.js": "0.2.0",
     "mocha": "1.7.4",

src/cache.coffee

@@ -155,6 +155,11 @@ class Cache
       # Return the value even if it's stale, we want the result ASAP
       wrappedValue?.d ? @staleOrPending[key]
 
-    @getWrapped(key).then(verifyFreshness).nodeify cb
+    handleError = (error) ->
+      # we should let the refreshValue method work if getWrapped has problems
+      # tracking backend errors should be done with wrapping your backend clients
+      return null
+
+    @getWrapped(key).catch(handleError).then(verifyFreshness).nodeify cb
 
 module.exports = Cache

test/cache.coffee

@@ -1,9 +1,9 @@
 
 expect = require 'expect.js'
+bond = require 'bondjs'
 
 Q = require 'q'
 {defaults} = require 'underscore'
-
 Cache = require '../lib/cache'
 cached = require '../lib/cached'
 
@@ -138,3 +138,16 @@ describe 'Cache', ->
             done()
 
           cache.getOrElse 'bad_keys', errorGenerator, freshFor: 1, theCallback
+
+        it 'handles thrown get errors by falling back on the value refresher', (done) ->
+          valueGenerator = cached.deferred (cb) ->
+            cb null, 'fresh cats'
+
+          theCallback = (err, data) ->
+            expect(err).to.be null
+            expect(data).to.be 'fresh cats'
+            done()
+
+          bond(cache, 'getWrapped').return Q.reject new Error('backend troubles')
+
+          cache.getOrElse 'bad_get', valueGenerator, freshFor: 5, theCallback