Replace most uses of null with undefined

.eslintrc.js

@@ -69,6 +69,7 @@ module.exports = {
     ],
     // Should use our logger anytime you want logs that persist. Otherwise use console only in testing
     'no-console': 'warn',
+    'no-null/no-null': 2,
     'no-plusplus': ['error', { allowForLoopAfterthoughts: true }],
     'no-type-assertion/no-type-assertion': 'error',
     'prettier/prettier': ['warn', { tabWidth: 2, trailingComma: 'all' }],
@@ -88,7 +89,7 @@ module.exports = {
     tsconfigRootDir: __dirname,
     createDefaultProgram: true,
   },
-  plugins: ['@typescript-eslint', 'no-type-assertion'],
+  plugins: ['@typescript-eslint', 'no-type-assertion', 'no-null'],
   settings: {
     'import/resolver': {
       // See https://github.com/benmosher/eslint-plugin-import/issues/1396#issuecomment-575727774 for line below

extensions/src/c-sharp-provider-test/manifest.json

@@ -4,6 +4,6 @@
   "description": "C# Data Provider Test Types for Paranext - provided by C# data provider",
   "author": "Paranext",
   "license": "MIT",
-  "main": null,
+  "main": "",
   "activationEvents": []
 }

extensions/src/hello-someone/hello-someone.web-view.html

@@ -114,7 +114,7 @@
         // Update the 'people' display on load and on updates
         peopleDataProvider.subscribePeople(undefined, (people) => {
           const peopleData = document.getElementById('people-data');
-          const peopleString = JSON.stringify(people, null, 2);
+          const peopleString = papi.utils.serialize(people, undefined, 2);
           peopleData.textContent = papi.utils.htmlEncode(peopleString.replace(/"/g, '`'));
           print(peopleString);
         });

extensions/src/project-notes-data-provider/manifest.json

@@ -4,6 +4,6 @@
   "description": "Project Notes Data Provider for Paranext - provided by C# data provider",
   "author": "Paranext",
   "license": "MIT",
-  "main": null,
+  "main": "",
   "activationEvents": []
 }

extensions/src/resource-viewer/resource-viewer.d.ts

@@ -7,8 +7,9 @@ declare module 'papi-shared-types' {
      *
      * @param projectId Optional project ID of the resource to open. Prompts the user to select a
      *   resource project if not provided
-     * @returns WebView id for new Resource Viewer WebView or `null` if the user canceled the dialog
+     * @returns WebView id for new Resource Viewer WebView or `undefined` if the user canceled the
+     *   dialog
      */
-    'resourceViewer.open': (projectId: string | undefined) => Promise<string | null | undefined>;
+    'resourceViewer.open': (projectId: string | undefined) => Promise<string | undefined>;
   }
 }

extensions/src/resource-viewer/resource-viewer.ts

@@ -22,24 +22,22 @@ interface ResourceViewerOptions extends GetWebViewOptions {
  * Function to prompt for a project and open it in the resource viewer. Registered as a command
  * handler.
  */
-async function openResourceViewer(
-  projectId: string | undefined,
-): Promise<string | null | undefined> {
+async function openResourceViewer(projectId: string | undefined): Promise<string | undefined> {
   let projectIdForWebView = projectId;
   if (!projectIdForWebView) {
     const options: DialogOptions = {
       title: 'Select Resource',
       prompt: 'Choose the resource project to view:',
     };
-    projectIdForWebView = (await papi.dialogs.selectProject(options)) ?? undefined;
+    projectIdForWebView = await papi.dialogs.selectProject(options);
   }
   if (projectIdForWebView) {
     const options: ResourceViewerOptions = { projectId: projectIdForWebView };
     // REVIEW: If a resource viewer is already open for the selected project, we open another.
     // This matches the current behavior in P9, though it might not be what we want long-term.
     return papi.webViews.getWebView(resourceWebViewType, undefined, options);
   }
-  return null;
+  return undefined;
 }
 
 /** Simple web view provider that provides Resource web views when papi requests them */
@@ -58,7 +56,7 @@ const resourceWebViewProvider: IWebViewProvider = {
       getWebViewOptions.projectId ||
       // eslint-disable-next-line no-type-assertion/no-type-assertion
       (savedWebView.state?.projectId as string) ||
-      null;
+      undefined;
     return {
       title: projectId
         ? `Resource Viewer : ${

extensions/src/usfm-data-provider/manifest.json

@@ -4,6 +4,6 @@
   "description": "USFM Data Provider for Paranext - provided by C# data provider",
   "author": "Paranext",
   "license": "MIT",
-  "main": null,
+  "main": "",
   "activationEvents": []
 }

extensions/webpack/webpack.util.ts

@@ -207,9 +207,10 @@ type ExtensionManifest = {
   /**
    * The JavaScript file to run in the extension host.
    *
-   * Must be specified. Can be `null` if the extension does not have any JavaScript to run.
+   * Must be specified. Can be an empty string ('') if the extension does not have any JavaScript to
+   * run.
    */
-  main: string | null;
+  main: string;
   activationEvents: string[];
 };
 
@@ -224,8 +225,8 @@ export type ExtensionInfo = {
   /** The extension's version */
   version: string;
   /**
-   * Whether to skip this extension when building. If the manifest main is null, there is no
-   * JavaScript to build
+   * Whether to skip this extension when building. If the manifest main is an empty string, there is
+   * no JavaScript to build
    */
   skipBuildingJavaScript?: boolean;
 };
@@ -259,7 +260,7 @@ export async function getExtensions(): Promise<ExtensionInfo[]> {
       });
 
       // Get main file path from the manifest and return extension info
-      return extensionManifest.main !== null
+      return extensionManifest.main !== ''
         ? {
             dirName: extensionFolderName,
             entryFileName: path.parse(extensionManifest.main).name,

lib/papi-components/src/snackbar.component.tsx

@@ -30,9 +30,9 @@ export type SnackbarProps = PropsWithChildren<{
   /**
    * The number of milliseconds to wait before automatically calling onClose()
    *
-   * @default null
+   * @default undefined
    */
-  autoHideDuration?: number | null;
+  autoHideDuration?: number;
 
   /** Additional css classes to help with unique styling of the snackbar, external */
   className?: string;
@@ -61,7 +61,7 @@ export type SnackbarProps = PropsWithChildren<{
  * https://mui.com/material-ui/getting-started/overview/
  */
 function Snackbar({
-  autoHideDuration = null,
+  autoHideDuration = undefined,
   id,
   isOpen = false,
   className,
@@ -78,7 +78,7 @@ function Snackbar({
 
   return (
     <MuiSnackbar
-      autoHideDuration={autoHideDuration}
+      autoHideDuration={autoHideDuration ?? null}
       open={isOpen}
       onClose={onClose}
       anchorOrigin={anchorOrigin}

lib/papi-components/src/toolbar.component.tsx

@@ -87,8 +87,8 @@ export default function Toolbar({
             >
               <MenuIcon />
             </IconButton>
-          ) : null}
-          {children ? <div className="papi-menu-children">{children}</div> : null}
+          ) : undefined}
+          {children ? <div className="papi-menu-children">{children}</div> : undefined}
           {menu ? (
             <Drawer
               className={`papi-menu-drawer ${className ?? ''}`}
@@ -105,7 +105,7 @@ export default function Toolbar({
             >
               <GridMenu commandHandler={toolbarCommandHandler} columns={menu.columns} />
             </Drawer>
-          ) : null}
+          ) : undefined}
         </MuiToolbar>
       </AppBar>
     </div>