tracks/javascript/exercises/rna-transcription/example.js in trackler-2.0.6.25 vs tracks/javascript/exercises/rna-transcription/example.js in trackler-2.0.6.26

@@ -9,9 +9,10 @@
   A: 'U'
 };
 
 var transcribeDna = function(dna, lookupTable) {
   return dna.replace(/./g, function(dnaNucleotide) {
+    if (!(dnaNucleotide in lookupTable)) { throw Error('Invalid input'); }
     return lookupTable[dnaNucleotide];
   });
 }
 
 DnaTranscriber.prototype.toRna = function(dna) {