Change QTFastStart to recover gracefully if it encounters an error during bitstring matching

This fixes issues with internal errors when trying to serve the video

changelog.d/qtfaststart.fix

@@ -0,0 +1 @@
+MediaProxy Preview failures prevented when encountering certain video files

lib/pleroma/helpers/qt_fast_start.ex

@@ -40,6 +40,7 @@ defp fix(
          got_mdat,
          acc
        ) do
+    try do
       full_size = (size - 8) * 8
       <<data::bits-size(full_size), rest::bits>> = rest
 
@@ -50,6 +51,10 @@ defp fix(
       ]
 
       fix(rest, pos + size, got_moov || fourcc == "moov", got_mdat || fourcc == "mdat", acc)
+    rescue
+      _ ->
+        :abort
+    end
   end
 
   defp fix(<<>>, _pos, _, _, acc) do