Fix PDF generation error by handling None values in SMILES arrays

app.py

@@ -57,12 +57,17 @@ def generate_all_reactions_pdf():
         pdf.cell(200, 8, txt=f"Reaction {idx+1}: {row['name']}", ln=True)
         pdf.set_font("Arial", size=8)
         
+        # Handle potential None values in SMILES
+        reactants_smiles = [s for s in row['reactants_smiles'] if s is not None]
+        reagents_smiles = [s for s in row['reagents_smiles'] if s is not None]
+        products_smiles = [s for s in row['products_smiles'] if s is not None]
+        
         pdf.cell(200, 6, txt=f"Reactants: {', '.join(row['reactants'])}", ln=True)
-        pdf.cell(200, 6, txt=f"Reactants SMILES: {', '.join(row['reactants_smiles'])}", ln=True)
+        pdf.cell(200, 6, txt=f"Reactants SMILES: {', '.join(reactants_smiles) if reactants_smiles else 'None'}", ln=True)
         pdf.cell(200, 6, txt=f"Reagents: {', '.join(row['reagents']) if len(row['reagents']) > 0 else 'None'}", ln=True)
-        pdf.cell(200, 6, txt=f"Reagents SMILES: {', '.join(row['reagents_smiles']) if len(row['reagents_smiles']) > 0 else 'None'}", ln=True)
+        pdf.cell(200, 6, txt=f"Reagents SMILES: {', '.join(reagents_smiles) if reagents_smiles else 'None'}", ln=True)
         pdf.cell(200, 6, txt=f"Products: {', '.join(row['products'])}", ln=True)
-        pdf.cell(200, 6, txt=f"Products SMILES: {', '.join(row['products_smiles'])}", ln=True)
+        pdf.cell(200, 6, txt=f"Products SMILES: {', '.join(products_smiles) if products_smiles else 'None'}", ln=True)
         pdf.ln(5)
         
         # Check if we need a new page