feat: add separate exception for invalid api definition

npm/ng-packs/packages/schematics/src/enums/exception.ts

@@ -1,12 +1,14 @@
 export const enum Exception {
   FileNotFound = '[File Not Found] There is no file at "{0}" path.',
   InvalidModule = '[Invalid Module] Backend module "{0}" does not exist in API definition.',
+  InvalidApiDefinition = '[Invalid API Definition] The provided API definition is invalid.',
   InvalidWorkspace = '[Invalid Workspace] The angular.json should be a valid JSON file.',
   NoApi = '[API Not Available] Please double-check the URL in the source project environment and make sure your application is up and running.',
-  NoApiDefinition = '[API Definition Not Found] There is no valid API definition file at "{0}".',
+  NoApiDefinition = '[API Definition Not Found] There is no API definition file at "{0}".',
   NoProject = '[Project Not Found] Either define a default project in your workspace or specify the project name in schematics options.',
   NoTypeDefinition = '[Type Definition Not Found] There is no type definition for "{0}".',
   NoWorkspace = '[Workspace Not Found] Make sure you are running schematics at the root directory of your workspace and it has an angular.json file.',
   NoEnvironment = '[Environment Not Found] An environment file cannot be located in "{0}" project.',
   NoApiUrl = '[API URL Not Found] Cannot resolve API URL for "{1}" module from "{0}" project.',
+  NoRootNamespace = '[Root Namespace Not Found] Cannot resolve root namespace for "{1}" module from "{0}" project.',
 }