compiler: add UnwrapNoneError exception

artiq/compiler/embedding.py

@@ -114,6 +114,7 @@ class EmbeddingMap:
             "0:ValueError",
             "0:ZeroDivisionError",
             "0:LinAlgError",
+            "UnwrapNoneError",
         ])
 
     def preallocate_runtime_exception_names(self, names):

artiq/coredevice/exceptions.py

@@ -182,3 +182,8 @@ class I2CError(Exception):
 class SPIError(Exception):
     """Raised when a SPI transaction fails."""
     artiq_builtin = True
+
+
+class UnwrapNoneError(Exception):
+    """Raised when unwrapping a none Option."""
+    artiq_builtin = True