Update app.py

app.py

@@ -30,7 +30,7 @@ def license_plate_detect(img):
 
 def read_license_number(img):
     boxes = license_plate_detect(img)
-    if boxes:
+    if boxes is not None:
         image = Image.fromarray(img)
         return [pytesseract.image_to_string(
                     image.crop(bbox.tolist()))
@@ -71,7 +71,7 @@ def check_solarplant_broken(image):
 
 def greet(img):
     boxes = license_plate_detect(img)
-    if boxes:
+    if boxes is not None:
         return (seg,
                 "車牌： " + '; '.join(lns) + "\n\n" \
                 + "類型： "+ check_solarplant_installed_by_image(img, True) + "\n\n" \