Fix stitched map images sometimes rendering garbage

CHANGELOG.md

@@ -45,6 +45,7 @@ The **"Breaking Changes"** listed below are changes that have been made in the d
 - Fix the map list filter retaining text between project open/close.
 - Fix the map list mishandling value gaps when sorting by Area.
 - Fix a freeze on startup if project values are defined with mismatched parentheses.
+- Fix stitched map images sometimes rendering garbage
 
 ## [5.4.1] - 2024-03-21
 ### Fixed

src/ui/mapimageexporter.cpp

@@ -309,6 +309,7 @@ QPixmap MapImageExporter::getStitchedImage(QProgressDialog *progress, bool inclu
     progress->setMaximum(stitchedMaps.size());
     int numDrawn = 0;
     QPixmap stitchedPixmap((maxX - minX) * 16, (maxY - minY) * 16);
+    stitchedPixmap.fill(Qt::black);
     QPainter painter(&stitchedPixmap);
     for (StitchedMap map : stitchedMaps) {
         if (progress->wasCanceled()) {