Fix doughsay#86

Has been running now for a while without showing crashes on object / deletion, whether from in-game destroy() or from the exterior (e.g. manual file removal). We get a warning log in both cases.

src/lib/fs-db.js

@@ -51,7 +51,11 @@ class FsDb {
       this.watcher
         .on('add', this.onFileAdded.bind(this))
         .on('change', this.onFileChanged.bind(this))
-        .on('unlink', this.onFileRemoved.bind(this));
+        .on('unlink', this.onFileRemoved.bind(this))
+        .on('error', (error) => { 
+          // On Windows notabbly, when a file is deleted from an extern process, an EPERM status may occur here, due to a temporary system file lock. Attempt at gracefully ignore the error, to avoid an uncaught exception.
+          this.logger.warn({ error }, 'file watcher error caught');
+        });
       this.emit('ready');
     });
   }
@@ -187,7 +191,14 @@ class FsDb {
 
   rmDir(relpath) {
     const filepath = this.toFilepath(relpath);
-    fs.rmdirSync(filepath);
+    try {
+      fs.rmdirSync(filepath);
+    } catch (error) {
+       // At least two observed cases here:
+      // - ENOTEMPTY
+      // - ENOENT
+      this.logger.warn({ relpath, error }, 'file directory deletion failed');
+    }
   }
 
   // input expected to be a path to a directory only

src/lib/moo-db.js

@@ -197,13 +197,7 @@ class MooDB {
       }
     }
     this.fsdb.rm(this.filenameForObj(id));
-    try {
-        this.fsdb.rmDir(this.filepathToObj(id)); // cleanup; FsDb should do this for us, but it doesn't.
-    } catch (err) {
-        // DO NOTHING
-        // This is acceptable, since we allow objects to be organized in directories.
-        // HOWEVER, an empty directory might remain, if underlying objects are later destroyed.
-    }
+    this.fsdb.rmDir(this.filepathToObj(id)); // cleanup; FsDb should do this for us, but it doesn't.
   }
 
   markObjectDirty(id) {