Made indexer a bit more robust
diff --git a/lib/KorAP/Tokenizer/Spans.pm b/lib/KorAP/Tokenizer/Spans.pm
index 7574743..045cf76 100644
--- a/lib/KorAP/Tokenizer/Spans.pm
+++ b/lib/KorAP/Tokenizer/Spans.pm
@@ -15,6 +15,9 @@
 sub parse {
   my $self = shift;
   my $path = $self->path . $self->foundry . '/' . $self->layer . '.xml';
+
+  return unless -e $path;
+
   my $file = b($path)->slurp;
 
   # my $spans = Mojo::DOM->new($file);
diff --git a/lib/KorAP/Tokenizer/Tokens.pm b/lib/KorAP/Tokenizer/Tokens.pm
index b62d2bb..e3336a3 100644
--- a/lib/KorAP/Tokenizer/Tokens.pm
+++ b/lib/KorAP/Tokenizer/Tokens.pm
@@ -14,6 +14,9 @@
 sub parse {
   my $self = shift;
   my $path = $self->path . $self->foundry . '/' . $self->layer . '.xml';
+
+  return unless -e $path;
+
   my $file = b($path)->slurp;
 
 #  my $spans = Mojo::DOM->new($file);