Merge pull request #1026 from umpirsky/patch-1

Better error message in Decoder

src/Intervention/Image/Gd/Decoder.php

@@ -57,7 +57,7 @@ class Decoder extends \Intervention\Image\AbstractDecoder
 
             default:
                 throw new NotReadableException(
-                    "Unsupported image type. GD driver is only able to decode JPG, PNG, GIF or WebP files."
+                    sprintf("Unsupported image type %s. GD driver is only able to decode JPG, PNG, GIF or WebP files.", strtolower($mime))
                 );
         }