Make not having grid metadata a warning instead of an error

There is plenty we can still do without the metadata, so completely
disabling access to the grid connection point if we don't have metadata
is too strict.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

src/frequenz/sdk/timeseries/grid.py

@@ -201,17 +201,16 @@ def initialize(
                 "No grid connection found for this microgrid. This is normal for an islanded microgrid."
             )
         case 1:
-            if grid_connections[0].metadata is None:
-                raise RuntimeError("Grid metadata is None")
-
-            if grid_connections[0].metadata.fuse is not None:
-                fuse = Fuse(
-                    max_current=Current.from_amperes(
-                        grid_connections[0].metadata.fuse.max_current
-                    )
+            metadata = grid_connections[0].metadata
+            if metadata is not None and metadata.fuse is not None:
+                fuse = Fuse(max_current=Current.from_amperes(metadata.fuse.max_current))
+
+            if metadata is None:
+                _logger.warning(
+                    "Unable to get grid metadata, the grid connection point is "
+                    "considered to have no fuse"
                 )
-
-            if fuse is None:
+            elif fuse is None:
                 _logger.warning("The grid connection point does not have a fuse")
         case _:
             raise RuntimeError(