Update app.py

app.py

@@ -23,7 +23,7 @@ def fold(id, sequence):
     try:
         dotbracket = ct2dot(ct_file)
     except:
-        dotbracket = ""
+        dotbracket = None
         structure_draw = "background.jpg"
         msg = "CT to dotbracket failed (check ct file)"
 
@@ -46,12 +46,12 @@ def run():
                         lines=3,    
                         value="GAUAAACCUUUAGCAAUAAACGAAAGUUUAACUAAGCCAUACUAACCCCAGGGUUGGUCAAUUUCGUGCCAGCCACCGCGGUCACACGAUUAACCCAAGCCAAUAGAAAUCGGCGUAAAGAGUGUUUUAGAUCAAUCCCCCAAUAAAGCUAAAAUUCACCUG")], 
         outputs=[
-            gr.Image(label="Structure", value="background.jpg"),
+            gr.Image(label="Structure"),
             gr.Textbox(label="Dotbracket structure",
                         lines=3),
             gr.File(label="Fasta file"), 
             gr.File(label="CT file"),
-            gr.Textbox(label=""),
+            gr.Textbox(label="Message"),
             ], 
         examples=[
             ["srp_Shig.flex._CP000266",	"CCGUCAGGUCCGGAAGGAAGCAGCGGUA"],