fix(core): added null check to packages metadata (#667)

Author: tgreyuk

packages/typedoc-plugin-markdown/src/theme/context/partials/page.header.ts

@@ -103,7 +103,7 @@ export function header(this: MarkdownThemeContext): string {
       : packageItem.name;
 
     const packagesMeta = this.getPackageMetaData(packageItem.name);
-    const entryModule = packagesMeta.options?.getValue('entryModule');
+    const entryModule = packagesMeta?.options?.getValue('entryModule');
     const packageEntryFile = ignoreScopes
       ? removeFirstScopedDirectory(
           `${packageItem.name}${path.sep}${entryFileName}`,

packages/typedoc-plugin-markdown/src/theme/markdown-themeContext.ts

@@ -117,7 +117,7 @@ export class MarkdownThemeContext {
    *
    * @internal
    */
-  getPackageMetaData(packageName: string): PackageMetaData {
+  getPackageMetaData(packageName: string): PackageMetaData | undefined {
     return this.packagesMetaData[packageName];
   }