add try-except hint for gps decode error (#374)

* add try-except hint for gps decode error

* try-except in code samples to fix gps decode error

3-transport/lessons/1-location-tracking/code-gps-decode/pi/gps-sensor/app.py

@@ -22,10 +22,14 @@ def print_gps_data(line):
         print(f'{lat},{lon} - from {msg.num_sats} satellites')
 
 while True:
-    line = serial.readline().decode('utf-8')
+    try:
+        line = serial.readline().decode('utf-8')
+
+        while len(line) > 0:
+            print_gps_data(line)
+            line = serial.readline().decode('utf-8')
 
-    while len(line) > 0:
+    except UnicodeDecodeError:
-        print_gps_data(line)
         line = serial.readline().decode('utf-8')
 
     time.sleep(1)

3-transport/lessons/1-location-tracking/code-gps/pi/gps-sensor/app.py

@@ -9,10 +9,14 @@ def print_gps_data():
     print(line.rstrip())
 
 while True:
-    line = serial.readline().decode('utf-8')
+    try:
+        line = serial.readline().decode('utf-8')
+
+        while len(line) > 0:
+            print_gps_data()
+            line = serial.readline().decode('utf-8')
 
-    while len(line) > 0:
+    except UnicodeDecodeError:
-        print_gps_data()
         line = serial.readline().decode('utf-8')
 
     time.sleep(1)

3-transport/lessons/1-location-tracking/pi-gps-sensor.md

@@ -149,13 +149,31 @@ Program the device.
     $BDGSV,1,1,00*68
     ```
 
-    > If you get one of the following errors when stopping and restarting your code, kill the VS Code terminal, then launch a new one and try again.
+    > If you get one of the following errors when stopping and restarting your code, add a `try - except` block to your while loop.
 
       ```output
       UnicodeDecodeError: 'utf-8' codec can't decode byte 0x93 in position 0: invalid start byte
       UnicodeDecodeError: 'utf-8' codec can't decode byte 0xf1 in position 0: invalid continuation byte
       ```
 
+    ```python
+    while True:
+        try:
+            line = serial.readline().decode('utf-8')
+              
+            while len(line) > 0:
+                print_gps_data()
+                line = serial.readline().decode('utf-8')
+      
+        # There's a random chance the first byte being read is part way through a character.
+        # Read another full line and continue.
+
+        except UnicodeDecodeError:
+            line = serial.readline().decode('utf-8')
+
+    time.sleep(1)
+    ```
+
 > 💁 You can find this code in the [code-gps/pi](code-gps/pi) folder.
 
 😀 Your GPS sensor program was a success!