database disk image is malformed & Unhandled exception: MemoryError

### Step 1: Please describe your environment

* ZeroNet version: 4486
* Operating system: Raspbian

### Step 2: Describe the problem:

@HelloZeroNet
Zeronet pages fails to load dynamic content (from DB) so i extracted ERROR lines from the debug.log and sorted removing duplicates, this is result:

```
ERROR Site:1ADQAH..g6aA WebSocket receive error: OSError: [Errno 113] No route to host in UiWebsocket.py line 71 > __init__.py line 80 > 86 > 48 > 105 > 125 > 156 > _socket3.py line 378
ERROR Site:1HeLLo..Tf3D WebSocket receive error: OSError: [Errno 113] No route to host in UiWebsocket.py line 71 > __init__.py line 80 > 86 > 48 > 105 > 125 > 156 > _socket3.py line 378
ERROR Site:1MWkQT..72fR Announce to 5 trackers in 130.400s, failed
ERROR Site:1uPDaT..NACf WebSocket handleRequest error: MemoryError: in UiWebsocket.py line 79 > 215 > 341 > 1133 > SiteManager.py line 124 > helper.py line 52 > re.py line 192
ERROR - Unhandled exception: DatabaseError: database disk image is malformed in greenlet.py line 766 > helper.py line 234 > Chart/ChartDb.py line 130 > Db.py line 150 > DbCursor.py line 105
ERROR - Unhandled exception: KeyError: 'data/users/19ZYUMmjE6hvT25iPzre4LMmx55aAZ5C3y/content.json' in greenlet.py line 766 > Pooled.py line 12 > Bigfile/BigfilePlugin.py line 804 > 833 > Site.py line 803 > 767 > Bigfile/BigfilePlugin.py line 258 > ContentManager.py line 408 > ContentDbDict.py line 116
ERROR - Unhandled exception: KeyError: 'data/users/1Cz94uug7y5gXzxKUzSpT5Cm2k8dM5KPDT/content.json' in greenlet.py line 766 > Pooled.py line 12 > Bigfile/BigfilePlugin.py line 804 > 833 > Site.py line 803 > 767 > Bigfile/BigfilePlugin.py line 258 > ContentManager.py line 408 > ContentDbDict.py line 116
ERROR - Unhandled exception: MemoryError: in greenlet.py line 766 > FileServer.py line 228 > Noparallel.py line 62 > 55 > Site.py line 509
ERROR - Unhandled exception: MemoryError: in greenlet.py line 766 > OptionalManager/UiWebsocketPlugin.py line 46 > OptionalManager/ContentDbPlugin.py line 243 > collections/__init__.py line 566 > 653
ERROR - Unhandled exception: MemoryError: in greenlet.py line 766 > OptionalManager/UiWebsocketPlugin.py line 46 > OptionalManager/ContentDbPlugin.py line 256
ERROR - Unhandled exception: MemoryError: in greenlet.py line 766 > SiteManager.py line 124 > helper.py line 52 > re.py line 192
ERROR - Unhandled exception: MemoryError: in greenlet.py line 766 > SiteManager.py line 138 > 124 > helper.py line 43 > json/__init__.py line 238 > json/encoder.py line 202
ERROR - Unhandled exception: UnicodeEncodeError: 'latin-1' codec can't encode characters in position 99-109: ordinal not in range(256) in greenlet.py line 766 > Bigfile/BigfilePlugin.py line 833 > Site.py line 785 > FilePack/FilePackPlugin.py line 106 > SiteStorage.py line 390 > genericpath.py line 30
```

Please do you see any helpful information that can fix something or what do you suggest to try?
Should i "just" quit ZN, delete content.db file and start it? Or something else i can try in order to prevent this issue in future?