Throw error on run task when MC dep is out-of-date

This is the same error for when the MC dep is out-of-date for the
relevant source set's compileJava task.

Author: Jonathing

src/main/java/net/minecraftforge/gradle/internal/ForgeGradleProblems.java

@@ -128,7 +128,7 @@ RuntimeException changingMinecraftDependency(Dependency dependency) {
 
     //region Minecraft Maven
     RuntimeException mavenizerOutOfDateCompile(Object dependency) {
-        return this.throwing(new IllegalStateException(), "mavenizer-out-of-date", "Minecraft Mavenizer is out-of-date", spec -> spec
+        return this.throwing(new IllegalStateException(), "mavenizer-out-of-date-for-compile", "Minecraft Mavenizer is out-of-date", spec -> spec
             .details("""
                 Gradle cannot compile your sources because the Minecraft Mavenizer is out-of-date.
                 The Mavenizer must be re-run in order for the changes made to the Minecraft dependency to take effect.
@@ -142,6 +142,21 @@ RuntimeException mavenizerOutOfDateCompile(Object dependency) {
             .solution(HELP_MESSAGE));
     }
 
+    RuntimeException mavenizerOutOfDateRunTask(Object dependency) {
+        return this.throwing(new IllegalStateException(), "mavenizer-out-of-date-for-run", "Minecraft Mavenizer is out-of-date", spec -> spec
+            .details("""
+                Gradle cannot run the game with Slime Launcher because the Minecraft Mavenizer is out-of-date.
+                The Mavenizer must be re-run in order for the changes made to the Minecraft dependency to take effect.
+                Affected dependency: '%s'"""
+                .formatted(dependency))
+            .severity(Severity.ERROR)
+            .solution("Re-import your project in your IDE, as this will automatically synchronize the Mavenizer.")
+            .solution("Run `gradlew` with no arguments, as this will automatically synchronize the Mavenizer.")
+            .solution("Manually run the `syncMavenizer` task, located in the 'Build Setup' group.")
+            .solution("Temporary revert any edits to the Minecraft dependency until the Mavenizer is re-run.")
+            .solution(HELP_MESSAGE));
+    }
+
     void reportMcMavenNotDeclared() {
         if (!this.test("net.minecraftforge.gradle.warnings.repository.missing.mavenizer")) return;
 

src/main/java/net/minecraftforge/gradle/internal/MinecraftDependencyImpl.java

@@ -176,6 +176,18 @@ public void handle(SourceSet sourceSet) {
         this.sourceSetName = sourceSet.getName();
     }
 
+    void handle(TaskProvider<SlimeLauncherExec> runTask) {
+        var problems = this.problems;
+        var asString = this.asString.get();
+        var dependencyOutput = this.mavenizerOutput.map(dir -> dir.dir(this.asPath)).get().get().getAsFile();
+        runTask.configure(task -> {
+            task.doFirst(t -> {
+                if (!dependencyOutput.exists())
+                    throw problems.mavenizerOutOfDateRunTask(asString);
+            });
+        });
+    }
+
     @Override
     public MinecraftMappings getMappings() {
         try {

src/main/java/net/minecraftforge/gradle/internal/MinecraftExtensionImpl.java

@@ -268,7 +268,10 @@ private void finish(Project project) {
                         assert minecraftDependency != null;
 
                         var impl = (MinecraftDependencyImpl) minecraftDependency;
-                        this.runs.forEach(options -> SlimeLauncherExec.register(project, sourceSet, options, impl.module.get(), impl.version.get(), impl.asPath.get(), impl.asString.get(), single));
+                        this.runs.forEach(options -> {
+                            var task = SlimeLauncherExec.register(project, sourceSet, options, impl.module.get(), impl.version.get(), impl.asPath.get(), impl.asString.get(), single);
+                            impl.handle(task);
+                        });
                     }
                 });
             }

src/main/java/net/minecraftforge/gradle/internal/SlimeLauncherExec.java

@@ -37,7 +37,7 @@
 import java.util.Map;
 
 abstract class SlimeLauncherExec extends JavaExec implements ForgeGradleTask, HasPublicType {
-    static void register(Project project, SourceSet sourceSet, SlimeLauncherOptionsImpl options, ModuleIdentifier module, String version, String asPath, String asString, boolean single) {
+    static TaskProvider<SlimeLauncherExec> register(Project project, SourceSet sourceSet, SlimeLauncherOptionsImpl options, ModuleIdentifier module, String version, String asPath, String asString, boolean single) {
         TaskProvider<SlimeLauncherMetadata> metadata;
         {
             TaskProvider<SlimeLauncherMetadata> t;
@@ -67,7 +67,7 @@ static void register(Project project, SourceSet sourceSet, SlimeLauncherOptionsI
         }
 
         var taskName = sourceSet.getTaskName("run", options.getName()) + (single ? "" : "for" + Util.dependencyToCamelCase(module));
-        project.getTasks().register(taskName, SlimeLauncherExec.class, task -> {
+        return project.getTasks().register(taskName, SlimeLauncherExec.class, task -> {
             task.getRunName().set(options.getName());
             task.setDescription("Runs the '%s' Slime Launcher run configuration.".formatted(options.getName()));