better error checking

src/commands/git_secret_cat.sh

@@ -36,5 +36,8 @@ function cat {
 
     # The parameters are: filename, write-to-file, force, homedir, passphrase
     _decrypt "$path" "0" "0" "$homedir" "$passphrase"
+    if [[ "$?" ne "0" ]]; then
+      _abort( "error decrypting $(filename): $?" )
+    fi
   done
 }