Only catch error if provider module itself does not exist

Fixes DevExpress#4522 and DevExpress#4673.

First uses `require.resolve`, which will only throw an error if the provider module itself doesn't exist. If it does exist, we then use `require` to load the module, not catching errors. That way, any errors caused by a 3rd party dependency will show up.

src/browser/provider/pool.js

@@ -69,14 +69,19 @@ export default {
 
     _getProviderModule (providerName, moduleName) {
         try {
-            const providerObject = require(moduleName);
-
-            this.addProvider(providerName, providerObject);
-            return this._getProviderFromCache(providerName);
+            // First, just check if the module exists
+            require.resolve(moduleName);
         }
         catch (e) {
+            // Module does not exist. Return null, and let the caller handle
             return null;
         }
+
+        // Load the module
+        const providerObject = require(moduleName);
+
+        this.addProvider(providerName, providerObject);
+        return this._getProviderFromCache(providerName);
     },
 
     _getProviderFromCache (providerName) {