SF-3318 Skip prompt when no changes made on draft source page (#3155)

Author: Nateowami

src/SIL.XForge.Scripture/ClientApp/src/app/translate/draft-generation/draft-sources/draft-sources.component.ts

@@ -219,6 +219,9 @@ export class DraftSourcesComponent extends DataLoadingComponent {
     index: number,
     paratextId: string | undefined
   ): void {
+    // When still loading projects, the project selectors will temporarily set the value to null
+    if (!this.isLoaded) return;
+
     const selectedProject: SelectableProject | null =
       this.projects?.find(p => p.paratextId === paratextId) ??
       this.resources?.find(r => r.paratextId === paratextId) ??

src/SIL.XForge.Scripture/ClientApp/src/assets/i18n/non_checking_en.json

@@ -278,7 +278,7 @@
     "close": "Close",
     "configure_draft_sources": "Configure draft sources",
     "confirm_language_codes": "Please confirm that the language codes are correct before saving.",
-    "discard_changes_confirmation": "Are you sure you want leave the page with unsaved changes?",
+    "discard_changes_confirmation": "Are you sure you want to leave the page with unsaved changes?",
     "draft_source": "Draft source",
     "generate_draft_from_language_model": "Generate draft from language model",
     "language_code": "Language code: ",