Fix empty template repo list issues

Prevents template repos list from being set to empty, and automatically
handles when the list ends up empty anyways.

Fixes: 2517

Author: DenWav

src/main/kotlin/MinecraftSettings.kt

@@ -3,7 +3,7 @@
  *
  * https://mcdev.io/
  *
- * Copyright (C) 2025 minecraft-dev
+ * Copyright (C) 2026 minecraft-dev
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published
@@ -90,7 +90,7 @@ class MinecraftSettings : PersistentStateComponent<MinecraftSettings.State> {
     override fun loadState(state: State) {
         this.state = state
         if (state.creatorTemplateRepos.isEmpty()) {
-            state.creatorTemplateRepos = listOf()
+            state.creatorTemplateRepos = listOf(TemplateRepo.makeBuiltinRepo())
         }
     }
 
@@ -140,7 +140,8 @@ class MinecraftSettings : PersistentStateComponent<MinecraftSettings.State> {
     var creatorTemplateRepos: List<TemplateRepo>
         get() = state.creatorTemplateRepos.map { it.copy() }
         set(creatorTemplateRepos) {
-            state.creatorTemplateRepos = creatorTemplateRepos.map { it.copy() }
+            state.creatorTemplateRepos = creatorTemplateRepos.ifEmpty { listOf(TemplateRepo.makeBuiltinRepo()) }
+                .map { it.copy() }
         }
 
     var creatorMavenRepos: List<MavenRepo>

src/main/kotlin/creator/custom/CustomPlatformStep.kt

@@ -215,7 +215,7 @@ class CustomPlatformStep(
     private fun initTemplates() {
         selectedTemplate = EmptyLoadedTemplate
 
-        templateRepoProperty.set(templateRepos.first())
+        templateRepoProperty.set(templateRepos.firstOrNull() ?: MinecraftSettings.TemplateRepo.makeBuiltinRepo())
 
         val indicator = CreatorProgressIndicator(
             templateProvidersLoadingProperty,

src/main/kotlin/creator/custom/TemplateRepoTable.kt

@@ -97,6 +97,7 @@ fun Row.templateRepoTable(
 
     val decoratedTable = ToolbarDecorator.createDecorator(table)
         .setPreferredSize(Dimension(JBUI.scale(300), JBUI.scale(200)))
+        .setRemoveActionUpdater { table.rowCount > 1 }
         .setEditActionUpdater {
             val selectedRepo = table.selection.firstOrNull()
                 ?: return@setEditActionUpdater false