Warn instead of silently defaulting when init cannot load the config

`init --systemd` read the effective configuration through a catch-all that
swallowed every exception and continued with a default `ServerConfig`. A
repository whose `.werkator.yml` failed validation for any reason then looked
exactly like one with no `publicBaseUrl`: the `.htaccess` and the maintenance
page were skipped without a word, during initial deployment setup of all times.

The fallback stays — the units are still generated — but the exception message
is now printed. The configuration is loaded once per run so the three readers
inside `createSystemdFiles` do not repeat the warning.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/main/kotlin/de/hoennig/werkator/commands/InitCommand.kt

@@ -48,6 +48,7 @@ class InitCommand(
     internal var javaExecutableResolver: () -> Path = { Paths.get(System.getProperty("java.home"), "bin", "java") }
 
     override fun run() {
+        cachedServerConfig = null
         val normalizedWorkingDir = workingDir.toAbsolutePath().normalize()
         val root =
             try {
@@ -298,12 +299,24 @@ class InitCommand(
      */
     private fun loadedSystemdConfig(): de.hoennig.werkator.config.SystemdConfig = loadedServerConfig().systemd
 
+    /** Loaded once per run, so a broken configuration is reported once and not per caller. */
+    private var cachedServerConfig: de.hoennig.werkator.config.ServerConfig? = null
+
+    /**
+     * A configuration error here is not fatal — the units are still generated with defaults —
+     * but it must not pass for "nothing configured": without the warning a broken `.werkator.yml`
+     * looks exactly like an unset `publicBaseUrl` and the host integration is skipped silently.
+     */
     private fun loadedServerConfig(): de.hoennig.werkator.config.ServerConfig =
+        cachedServerConfig ?: run {
             try {
                 configLoader.load(Paths.get(".")).server
-        } catch (_: Exception) {
+            } catch (e: Exception) {
+                println("Warning: the effective configuration could not be loaded (${e.message})")
+                println("  continuing with default server settings — check the generated unit and host files")
                 de.hoennig.werkator.config
                     .ServerConfig()
+            }.also { cachedServerConfig = it }
         }
 
     private fun createSystemdFiles(

src/test/kotlin/de/hoennig/werkator/commands/InitCommandTest.kt

@@ -252,5 +252,27 @@ class InitCommandTest : FunSpec() {
             // This should not throw IllegalArgumentException
             initCommand.run()
         }
+
+        test("--systemd warns once when the effective configuration cannot be loaded") {
+            val tempDir = Files.createTempDirectory("werkator-init-test")
+            val brokenLoader = mockk<de.hoennig.werkator.config.ConfigLoader>()
+            every { brokenLoader.load(any()) } throws IllegalStateException("gitea.owner is required")
+            val command = InitCommand(gitService, brokenLoader)
+            command.workingDir = tempDir
+            command.systemd = true
+            command.jarPathResolver = { Paths.get("/home/ci/bin/werkator.jar") }
+            command.javaExecutableResolver = { Paths.get("/usr/bin/java") }
+
+            every { gitService.getTopLevel(tempDir) } returns tempDir
+            every { gitService.getOriginUrl(tempDir) } returns "https://git.example.org/my-org/my-repo.git"
+
+            val console = captureConsole { command.run() }
+
+            console.stdout shouldContain "gitea.owner is required"
+            // the three readers of the configuration must not repeat the warning
+            console.stdout.windowed("Warning:".length).count { it == "Warning:" } shouldBe 1
+            // the units are still written with the defaults
+            tempDir.resolve(".git/werkator/${SystemdServiceFiles.unitName(tempDir)}").toFile().shouldExist()
+        }
     }
 }