fix: InvalidPathException when custom run directory is not valid

HMCL/src/main/java/org/jackhuang/hmcl/game/HMCLGameRepository.java

@@ -62,10 +62,16 @@ public class HMCLGameRepository extends DefaultGameRepository {
     @Override
     public File getRunDirectory(String id) {
         switch (getGameDirectoryType(id)) {
-            case VERSION_FOLDER: return getVersionRoot(id);
+            case VERSION_FOLDER:
-            case ROOT_FOLDER: return super.getRunDirectory(id);
+                return getVersionRoot(id);
-            case CUSTOM: return new File(getVersionSetting(id).getGameDir());
+            case ROOT_FOLDER:
-            default: throw new Error();
+                return super.getRunDirectory(id);
+            case CUSTOM:
+                File dir = new File(getVersionSetting(id).getGameDir());
+                if (!FileUtils.isValidPath(dir)) return getVersionRoot(id);
+                return dir;
+            default:
+                throw new Error();
         }
     }
 

HMCLCore/src/main/java/org/jackhuang/hmcl/util/io/FileUtils.java

@@ -390,4 +390,19 @@ public final class FileUtils {
                     result.add(it);
         return result;
     }
+
+    /**
+     * Tests whether the file is convertible to [java.nio.file.Path] or not.
+     *
+     * @param file the file to be tested
+     * @return true if the file is convertible to Path.
+     */
+    public static boolean isValidPath(File file) {
+        try {
+            file.toPath();
+            return true;
+        } catch (InvalidPathException ignored) {
+            return false;
+        }
+    }
 }