prefer undefined over null

src/domain/avatar.ts

@@ -51,10 +51,10 @@ export function getIdentifierColorNumber(id: string): number {
     return (hashCode(id) % 8) + 1;
 }
 
-export function getAvatarHttpUrl(avatarUrl: string, cssSize: number, platform: Platform, mediaRepository: MediaRepository): string | null {
+export function getAvatarHttpUrl(avatarUrl: string | undefined, cssSize: number, platform: Platform, mediaRepository: MediaRepository): string | undefined {
     if (avatarUrl) {
         const imageSize = cssSize * platform.devicePixelRatio;
         return mediaRepository.mxcUrlThumbnail(avatarUrl, imageSize, imageSize, "crop");
     }
-    return null;
+    return undefined;
 }

src/matrix/net/MediaRepository.ts

@@ -29,32 +29,31 @@ export class MediaRepository {
         this._platform = platform;
     }
 
-    mxcUrlThumbnail(url: string, width: number, height: number, method: "crop" | "scale"): string | null {
+    mxcUrlThumbnail(url: string, width: number, height: number, method: "crop" | "scale"): string | undefined {
         const parts = this._parseMxcUrl(url);
         if (parts) {
             const [serverName, mediaId] = parts;
             const httpUrl = `${this._homeserver}/_matrix/media/r0/thumbnail/${encodeURIComponent(serverName)}/${encodeURIComponent(mediaId)}`;
             return httpUrl + "?" + encodeQueryParams({width: Math.round(width), height: Math.round(height), method});
         }
-        return null;
+        return undefined;
     }
 
-    mxcUrl(url: string): string | null {
+    mxcUrl(url: string): string | undefined {
         const parts = this._parseMxcUrl(url);
         if (parts) {
             const [serverName, mediaId] = parts;
             return `${this._homeserver}/_matrix/media/r0/download/${encodeURIComponent(serverName)}/${encodeURIComponent(mediaId)}`;
-        } else {
-            return null;
         }
+        return undefined;
     }
 
-    private _parseMxcUrl(url: string): string[] | null {
+    private _parseMxcUrl(url: string): string[] | undefined {
         const prefix = "mxc://";
         if (url.startsWith(prefix)) {
             return url.substr(prefix.length).split("/", 2);
         } else {
-            return null;
+            return undefined;
         }
     }
 

src/platform/web/ui/general/TemplateView.ts

@@ -337,7 +337,7 @@ export class TemplateBuilder<T extends IObservableValue> {
     // Special case of mapView for a TemplateView.
     // Always creates a TemplateView, if this is optional depending
     // on mappedValue, use `if` or `mapView`
-    map<R>(mapFn: (value: T) => R, renderFn: (mapped: R, t: Builder<T>, vm: T) => ViewNode): ViewNode {
+    map<R>(mapFn: (value: T) => R, renderFn: (mapped: R, t: Builder<T>, vm: T) => ViewNode | undefined): ViewNode {
         return this.mapView(mapFn, mappedValue => {
             return new InlineTemplateView(this._value, (t, vm) => {
                 const rootNode = renderFn(mappedValue, t, vm);