Screenshot::delete() and Image::delete() should check if the file exists before attempting to

call unlink() on it. Fixes three php errors that occur during the unit tests.

include/image.php

@@ -391,7 +391,9 @@ class Image {
      */
     function delete()
     {
-        unlink($this->sFile);
+        // if the file exists, delete it
+        if(is_file($this->sFile))
+            unlink($this->sFile);
     }
 
     

include/screenshot.php

@@ -139,7 +139,12 @@ class Screenshot {
 
             $this->oScreenshotImage->delete();
             $this->oThumbnailImage->delete();
-            unlink(appdb_fullpath("/data/screenshots/originals/".$this->iScreenshotId));
+
+            // if the original file exists, delete it
+            $sOriginalFilename = appdb_fullpath("/data/screenshots/originals/".$this->iScreenshotId);
+            if(is_file($sOriginalFilename))
+              unlink($sOriginalFilename);
+
             if(!$bSilent)
                 $this->mailMaintainers(true);
         }