Cleanup potentially corrupt files on mappings error

src/main/java/net/fabricmc/loom/providers/MappingsProvider.java

@@ -55,6 +55,7 @@ import net.fabricmc.stitch.commands.tinyv2.CommandMergeTinyV2;
 import net.fabricmc.stitch.commands.tinyv2.CommandReorderTinyV2;
 import net.fabricmc.loom.processors.JarProcessorManager;
 import net.fabricmc.loom.processors.MinecraftProcessedProvider;
+import net.fabricmc.loom.util.DeletingFileVisitor;
 
 public class MappingsProvider extends DependencyProvider {
 	public MinecraftMappedProvider mappedProvider;
@@ -260,6 +261,18 @@ public class MappingsProvider extends DependencyProvider {
 		mappingsMixinExport = new File(getExtension().getProjectBuildCache(), "mixin-map-" + minecraftVersion + "-" + mappingsVersion + ".tiny");
 	}
 
+	public void cleanFiles() {
+		try {
+			Files.walkFileTree(mappingsStepsDir, new DeletingFileVisitor());
+			Files.deleteIfExists(baseTinyMappings);
+			mappingsMixinExport.delete();
+			tinyMappings.delete();
+			tinyMappingsJar.delete();
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+
 	@Override
 	public String getTargetConfig() {
 		return Constants.MAPPINGS;

src/main/java/net/fabricmc/loom/providers/MinecraftMappedProvider.java

@@ -65,7 +65,15 @@ public class MinecraftMappedProvider extends DependencyProvider {
 				minecraftIntermediaryJar.delete();
 			}
 
-			new MapJarsTiny().mapJars(minecraftProvider, this, this.minecraftMappedJar, this.minecraftIntermediaryJar, getProject());
+			try {
+				new MapJarsTiny().mapJars(minecraftProvider, this, this.minecraftMappedJar, this.minecraftIntermediaryJar, getProject());
+			} catch (Throwable t) {
+				//Cleanup some some things that may be in a bad state now
+				minecraftMappedJar.delete();
+				minecraftIntermediaryJar.delete();
+				getExtension().getMappingsProvider().cleanFiles();
+				throw new RuntimeException("Failed to remap minecraft", t);
+			}
 		}
 
 		if (!minecraftMappedJar.exists()) {

src/main/java/net/fabricmc/loom/task/CleanLoomMappings.java

@@ -41,6 +41,7 @@ public class CleanLoomMappings extends AbstractLoomTask {
 			extension.getMinecraftMappedProvider().getIntermediaryJar().delete();
 			extension.getMinecraftMappedProvider().getMappedJar().delete();
 			Files.walkFileTree(extension.getRootProjectBuildCache().toPath(), new DeletingFileVisitor());
+			getExtension().getMappingsProvider().cleanFiles();
 		} catch (IOException e) {
 			throw new RuntimeException(e);
 		}