refactor: make types more accurate

Author: robert-hebel-sb

src/types/system.ts

@@ -1,14 +1,19 @@
 import { PropChangedAction } from 'plugins/props-change-watcher/actions';
 import { Action } from 'types/actions';
+import { ComponentType } from 'react';
 
 export interface SystemValues {
-  getComponent: () => void;
+  getComponent: (
+    componentName: string,
+    container?: boolean,
+    config?: object
+  ) => ComponentType | null;
   editorSelectors: {
     selectContent: () => string;
     selectInferFileNameWithExtensionFromContent: () => string;
   };
   editorActions: {
-    convertContentToJSON: (content: string) => Action<string>;
+    convertContentToJSON: (content: string) => Action<string | Error>;
     setContent: (content: string) => Action<string>;
     propChanged: PropChangedAction;
   };