fix(CLI): Do not validate configuration with plugin .. commands

lib/Serverless.js

@@ -425,17 +425,18 @@ class Serverless {
       }
     }
 
-    // merge arrays after variables have been populated
-    // (https://github.com/serverless/serverless/issues/3511)
-    this.service.mergeArrays();
+    if (resolveCliInput().commands[0] !== 'plugin') {
+      // merge arrays after variables have been populated
+      // (https://github.com/serverless/serverless/issues/3511)
+      this.service.mergeArrays();
 
-    // populate function names after variables are loaded in case functions were externalized
-    // (https://github.com/serverless/serverless/issues/2997)
-    this.service.setFunctionNames(this.processedInput.options);
-
-    // If in context of service, validate the service configuration
-    if (this.serviceDir) this.service.validate();
+      // populate function names after variables are loaded in case functions were externalized
+      // (https://github.com/serverless/serverless/issues/2997)
+      this.service.setFunctionNames(this.processedInput.options);
 
+      // If in context of service, validate the service configuration
+      if (this.serviceDir) this.service.validate();
+    }
     // trigger the plugin lifecycle when there's something which should be processed
     await this.pluginManager.run(this.processedInput.commands);
   }

lib/classes/PluginManager.js

@@ -605,9 +605,11 @@ class PluginManager {
    * Called by the CLI to start a public command.
    */
   async run(commandsArray) {
-    // first initialize hooks
-    for (const { hook } of this.getHooks(['initialize'])) {
-      await hook();
+    if (resolveCliInput().commands[0] !== 'plugin') {
+      // first initialize hooks
+      for (const { hook } of this.getHooks(['initialize'])) {
+        await hook();
+      }
     }
 
     let deferredBackendNotificationRequest;